You have all undoubtedly killed a pack of wolves or spiders and received a bunch of pelts or venom sacks and said "Yipee, stuff to sell"  I have a suspicion that this stuff isn't intended to be just a source of extra cash, but just in case, here's an idea.

So you have a bunch of wolf pelts and you take them to the store.  Now you could just sell them, but the store owner also has a wolf pelt armor that costs 4 pelts and X $$$.  Maybe it is like leather armor, but a little better and with cold resistance.  There is also a 1x use weapon poison vial that costs 1 venom sack and $$$ and will cause poison damage for the duration of the combat.  Use your imagination on the other types of loot.

The other advantage of something like this is you would be less likely to just sell the loot.  As it is, you can easily run a loot-based economy with minimal or no taxes.