Correct selling prices of creature merchants

apps/openmw/mwgui/tradewindow.cpp

@@ -484,7 +484,7 @@ namespace MWGui
             const int basePrice = getEffectiveValue(itemStack.mBase, itemStack.mCount);
             const int cap = static_cast<int>(std::max(1.f, 0.75f * basePrice)); // Maximum selling price -- 75% of the base
             const int sellingPrice = MWBase::Environment::get().getMechanicsManager()->getBarterOffer(mPtr, basePrice, false);
-            merchantOffer += std::min(cap, sellingPrice);
+            merchantOffer += mPtr.getClass().isNpc() ? std::min(cap, sellingPrice) : sellingPrice;
         }
 
         int diff = merchantOffer - mCurrentMerchantOffer;