[salesman]

Instead of limiting the amount that can be sold, set limits on the prices at which they can be sold for. That's the idea behind the pawn shop, and it should be able to apply to player-owned businesses as well. Limiting the number of guns is never a good thing because then players gain control of the prices, and we're back where we started where the only way to get an item is by finding a player that already has it.

Set a minimum and maximum price that they can sell it for, and then allow the pawn shop to buy it back for a price less than the minimum sale price. You then have a clearly defined value (or value range) for the item. This would help ensure that players go to the stores to buy items instead of massing out "Buying _____ for 150k!" because the item will always be worth about the same price.