diff --git a/apps/openmw/mwclass/apparatus.cpp b/apps/openmw/mwclass/apparatus.cpp
index 851a5ae36..32c127731 100644
--- a/apps/openmw/mwclass/apparatus.cpp
+++ b/apps/openmw/mwclass/apparatus.cpp
@@ -159,4 +159,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mAppas.insert(*ref), &cell);
     }
+
+    bool Apparatus::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Apparatus;
+    }
 }
diff --git a/apps/openmw/mwclass/apparatus.hpp b/apps/openmw/mwclass/apparatus.hpp
index 7045f62d6..d4917c618 100644
--- a/apps/openmw/mwclass/apparatus.hpp
+++ b/apps/openmw/mwclass/apparatus.hpp
@@ -54,6 +54,8 @@ namespace MWClass
             ///< Generate action for using via inventory menu
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/armor.cpp b/apps/openmw/mwclass/armor.cpp
index 320944d3c..e62985d3d 100644
--- a/apps/openmw/mwclass/armor.cpp
+++ b/apps/openmw/mwclass/armor.cpp
@@ -315,4 +315,9 @@ namespace MWClass
 
         return ref->mBase->mData.mEnchant;
     }
+
+    bool Armor::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Armor;
+    }
 }
diff --git a/apps/openmw/mwclass/armor.hpp b/apps/openmw/mwclass/armor.hpp
index 65f49abb7..16905d65c 100644
--- a/apps/openmw/mwclass/armor.hpp
+++ b/apps/openmw/mwclass/armor.hpp
@@ -74,6 +74,8 @@ namespace MWClass
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
 
             virtual short getEnchantmentPoints (const MWWorld::Ptr& ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/book.cpp b/apps/openmw/mwclass/book.cpp
index 85b006160..b658295f8 100644
--- a/apps/openmw/mwclass/book.cpp
+++ b/apps/openmw/mwclass/book.cpp
@@ -183,4 +183,9 @@ namespace MWClass
 
         return ref->mBase->mData.mEnchant;
     }
+
+    bool Book::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Books;
+    }
 }
diff --git a/apps/openmw/mwclass/book.hpp b/apps/openmw/mwclass/book.hpp
index 29e3de036..3f083f552 100644
--- a/apps/openmw/mwclass/book.hpp
+++ b/apps/openmw/mwclass/book.hpp
@@ -59,6 +59,8 @@ namespace MWClass
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
 
             virtual short getEnchantmentPoints (const MWWorld::Ptr& ptr) const; 
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/clothing.cpp b/apps/openmw/mwclass/clothing.cpp
index abad26767..98480f06f 100644
--- a/apps/openmw/mwclass/clothing.cpp
+++ b/apps/openmw/mwclass/clothing.cpp
@@ -262,4 +262,9 @@ namespace MWClass
 
         return ref->mBase->mData.mEnchant;
     }
+
+    bool Clothing::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Clothing;
+    }
 }
diff --git a/apps/openmw/mwclass/clothing.hpp b/apps/openmw/mwclass/clothing.hpp
index c3ef22f11..2e5bb424f 100644
--- a/apps/openmw/mwclass/clothing.hpp
+++ b/apps/openmw/mwclass/clothing.hpp
@@ -68,6 +68,8 @@ namespace MWClass
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
 
             virtual short getEnchantmentPoints (const MWWorld::Ptr& ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/ingredient.cpp b/apps/openmw/mwclass/ingredient.cpp
index 14cf6ff6f..0afe60e0e 100644
--- a/apps/openmw/mwclass/ingredient.cpp
+++ b/apps/openmw/mwclass/ingredient.cpp
@@ -197,4 +197,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mIngreds.insert(*ref), &cell);
     }
+
+    bool Ingredient::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Ingredients;
+    }
 }
diff --git a/apps/openmw/mwclass/ingredient.hpp b/apps/openmw/mwclass/ingredient.hpp
index 0afd202fb..d27a7cbb0 100644
--- a/apps/openmw/mwclass/ingredient.hpp
+++ b/apps/openmw/mwclass/ingredient.hpp
@@ -56,6 +56,8 @@ namespace MWClass
             ///< Return name of inventory icon.
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/light.cpp b/apps/openmw/mwclass/light.cpp
index 746665772..306c6bbb6 100644
--- a/apps/openmw/mwclass/light.cpp
+++ b/apps/openmw/mwclass/light.cpp
@@ -203,4 +203,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mLights.insert(*ref), &cell);
     }
+
+    bool Light::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Lights;
+    }
 }
diff --git a/apps/openmw/mwclass/light.hpp b/apps/openmw/mwclass/light.hpp
index 640e1705b..7d919f75d 100644
--- a/apps/openmw/mwclass/light.hpp
+++ b/apps/openmw/mwclass/light.hpp
@@ -57,6 +57,8 @@ namespace MWClass
             ///< Generate action for using via inventory menu
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/lockpick.cpp b/apps/openmw/mwclass/lockpick.cpp
index 201572696..bfbf10756 100644
--- a/apps/openmw/mwclass/lockpick.cpp
+++ b/apps/openmw/mwclass/lockpick.cpp
@@ -176,4 +176,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mLockpicks.insert(*ref), &cell);
     }
+
+    bool Lockpick::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Picks;
+    }
 }
diff --git a/apps/openmw/mwclass/lockpick.hpp b/apps/openmw/mwclass/lockpick.hpp
index 0961b55b2..edd884a3e 100644
--- a/apps/openmw/mwclass/lockpick.hpp
+++ b/apps/openmw/mwclass/lockpick.hpp
@@ -57,6 +57,8 @@ namespace MWClass
             ///< Generate action for using via inventory menu
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/misc.cpp b/apps/openmw/mwclass/misc.cpp
index 8cfac1a68..02307cc02 100644
--- a/apps/openmw/mwclass/misc.cpp
+++ b/apps/openmw/mwclass/misc.cpp
@@ -246,4 +246,12 @@ namespace MWClass
             return boost::shared_ptr<MWWorld::Action>(new MWWorld::ActionSoulgem(ptr));
     }
 
+    bool Miscellaneous::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        MWWorld::LiveCellRef<ESM::Miscellaneous> *ref =
+            item.get<ESM::Miscellaneous>();
+
+        return !ref->mBase->mData.mIsKey && (npcServices & ESM::NPC::Misc);
+    }
+
 }
diff --git a/apps/openmw/mwclass/misc.hpp b/apps/openmw/mwclass/misc.hpp
index 12a50af19..ba00900bd 100644
--- a/apps/openmw/mwclass/misc.hpp
+++ b/apps/openmw/mwclass/misc.hpp
@@ -53,6 +53,8 @@ namespace MWClass
             virtual boost::shared_ptr<MWWorld::Action> use (const MWWorld::Ptr& ptr)
                 const;
             ///< Generate action for using via inventory menu
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/potion.cpp b/apps/openmw/mwclass/potion.cpp
index 37461ed90..ad2826ea8 100644
--- a/apps/openmw/mwclass/potion.cpp
+++ b/apps/openmw/mwclass/potion.cpp
@@ -194,4 +194,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mPotions.insert(*ref), &cell);
     }
+
+    bool Potion::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Potions;
+    }
 }
diff --git a/apps/openmw/mwclass/potion.hpp b/apps/openmw/mwclass/potion.hpp
index d595f7e69..845795d0e 100644
--- a/apps/openmw/mwclass/potion.hpp
+++ b/apps/openmw/mwclass/potion.hpp
@@ -52,6 +52,8 @@ namespace MWClass
             ///< Return name of inventory icon.
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/probe.cpp b/apps/openmw/mwclass/probe.cpp
index e4533af65..4ec6a8340 100644
--- a/apps/openmw/mwclass/probe.cpp
+++ b/apps/openmw/mwclass/probe.cpp
@@ -175,4 +175,9 @@ namespace MWClass
 
         return MWWorld::Ptr(&cell.mProbes.insert(*ref), &cell);
     }
+
+    bool Probe::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Probes;
+    }
 }
diff --git a/apps/openmw/mwclass/probe.hpp b/apps/openmw/mwclass/probe.hpp
index d9f90baf6..75ebaa01c 100644
--- a/apps/openmw/mwclass/probe.hpp
+++ b/apps/openmw/mwclass/probe.hpp
@@ -57,6 +57,8 @@ namespace MWClass
             ///< Generate action for using via inventory menu
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/repair.cpp b/apps/openmw/mwclass/repair.cpp
index bafedee88..36e706825 100644
--- a/apps/openmw/mwclass/repair.cpp
+++ b/apps/openmw/mwclass/repair.cpp
@@ -175,4 +175,9 @@ namespace MWClass
     {
         return boost::shared_ptr<MWWorld::Action>(new MWWorld::ActionRepair(ptr));
     }
+
+    bool Repair::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::RepairItem;
+    }
 }
diff --git a/apps/openmw/mwclass/repair.hpp b/apps/openmw/mwclass/repair.hpp
index 3083c97e3..a545cf4d6 100644
--- a/apps/openmw/mwclass/repair.hpp
+++ b/apps/openmw/mwclass/repair.hpp
@@ -61,6 +61,8 @@ namespace MWClass
             virtual int getItemMaxHealth (const MWWorld::Ptr& ptr) const;
             ///< Return item max health or throw an exception, if class does not have item health
             /// (default implementation: throw an exceoption)
+
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
     };
 }
 
diff --git a/apps/openmw/mwclass/weapon.cpp b/apps/openmw/mwclass/weapon.cpp
index 0a527262f..3df1ced7d 100644
--- a/apps/openmw/mwclass/weapon.cpp
+++ b/apps/openmw/mwclass/weapon.cpp
@@ -409,4 +409,9 @@ namespace MWClass
 
         return ref->mBase->mData.mEnchant;
     }
+
+    bool Weapon::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return npcServices & ESM::NPC::Weapon;
+    }
 }
diff --git a/apps/openmw/mwclass/weapon.hpp b/apps/openmw/mwclass/weapon.hpp
index 4774bb50b..084ceeca2 100644
--- a/apps/openmw/mwclass/weapon.hpp
+++ b/apps/openmw/mwclass/weapon.hpp
@@ -73,6 +73,8 @@ namespace MWClass
 
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
 
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
+
             virtual short getEnchantmentPoints (const MWWorld::Ptr& ptr) const;
     };
 }
diff --git a/apps/openmw/mwgui/tradewindow.cpp b/apps/openmw/mwgui/tradewindow.cpp
index 81a29e69b..73904371e 100644
--- a/apps/openmw/mwgui/tradewindow.cpp
+++ b/apps/openmw/mwgui/tradewindow.cpp
@@ -356,32 +356,7 @@ namespace MWGui
                 services = ref->mBase->mAiData.mServices;
         }
 
-        /// \todo what about potions, there doesn't seem to be a flag for them??
-
-        if      (item.getTypeName() == typeid(ESM::Weapon).name())
-            return services & ESM::NPC::Weapon;
-        else if (item.getTypeName() == typeid(ESM::Armor).name())
-            return services & ESM::NPC::Armor;
-        else if (item.getTypeName() == typeid(ESM::Clothing).name())
-            return services & ESM::NPC::Clothing;
-        else if (item.getTypeName() == typeid(ESM::Book).name())
-            return services & ESM::NPC::Books;
-        else if (item.getTypeName() == typeid(ESM::Ingredient).name())
-            return services & ESM::NPC::Ingredients;
-        else if (item.getTypeName() == typeid(ESM::Lockpick).name())
-            return services & ESM::NPC::Picks;
-        else if (item.getTypeName() == typeid(ESM::Probe).name())
-            return services & ESM::NPC::Probes;
-        else if (item.getTypeName() == typeid(ESM::Light).name())
-            return services & ESM::NPC::Lights;
-        else if (item.getTypeName() == typeid(ESM::Apparatus).name())
-            return services & ESM::NPC::Apparatus;
-        else if (item.getTypeName() == typeid(ESM::Repair).name())
-            return services & ESM::NPC::RepairItem;
-        else if (item.getTypeName() == typeid(ESM::Miscellaneous).name())
-            return services & ESM::NPC::Misc;
-
-        return false;
+        return MWWorld::Class::get(item).canSell(item, services);
     }
 
     std::vector<MWWorld::Ptr> TradeWindow::itemsToIgnore()
diff --git a/apps/openmw/mwworld/class.cpp b/apps/openmw/mwworld/class.cpp
index 2dfa241b3..0f8d40e93 100644
--- a/apps/openmw/mwworld/class.cpp
+++ b/apps/openmw/mwworld/class.cpp
@@ -47,6 +47,11 @@ namespace MWWorld
         throw std::runtime_error ("class does not represent an actor");
     }
 
+    bool Class::canSell (const MWWorld::Ptr& item, int npcServices) const
+    {
+        return false;
+    }
+
     MWMechanics::CreatureStats& Class::getCreatureStats (const Ptr& ptr) const
     {
         throw std::runtime_error ("class does not have creature stats");
diff --git a/apps/openmw/mwworld/class.hpp b/apps/openmw/mwworld/class.hpp
index de4741e38..49e0ff003 100644
--- a/apps/openmw/mwworld/class.hpp
+++ b/apps/openmw/mwworld/class.hpp
@@ -238,6 +238,9 @@ namespace MWWorld
 
             virtual void adjustRotation(const MWWorld::Ptr& ptr,float& x,float& y,float& z) const;
 
+            virtual bool canSell (const MWWorld::Ptr& item, int npcServices) const;
+            ///< Determine whether or not \a item can be sold to an npc with the given \a npcServices
+
             virtual std::string getModel(const MWWorld::Ptr &ptr) const;
 
             virtual void applyEnchantment(const MWWorld::Ptr &ptr, const std::string& enchId, int enchCharge, const std::string& newName) const;
diff --git a/components/esm/loadnpc.hpp b/components/esm/loadnpc.hpp
index 46be29961..b30077f23 100644
--- a/components/esm/loadnpc.hpp
+++ b/components/esm/loadnpc.hpp
@@ -35,11 +35,11 @@ struct NPC
       Apparatus     = 0x00100,
       RepairItem    = 0x00200,
       Misc          = 0x00400,
+      Potions       = 0x02000,
 
       // Other services
       Spells        = 0x00800,
       MagicItems    = 0x01000,
-      Potions       = 0x02000,
       Training      = 0x04000, // What skills?
       Spellmaking   = 0x08000,
       Enchanting    = 0x10000,