How to get all the NPC’s money:
- Sell them lots of junk stuff.
- When they drop something it means that they are out of inventory space (or possibly at their weight limit?).
- Sell them whatever they dropped, again and again and again, until you get all their money.
Bottom line: Clearly NPC’s buying something just to drop it down is wrong behavior.
- Npc’s should only buy stuff if they have inventory space for it.
- When NPC’s have reached the max they can carry, they have to decide for themselves if the traded item(s) interest them enough to drop something else in order to get them.