There are some items in the game that you get from chests and can only get once. I think it would be cool to have a Pawn Shop where it's the only place that such items can be sold. Only these items that can be obtained once can be sold there and if you want it back you will need to pay a bit more than what you've sold it for. This gives you a way to sell unwanted items that clog your inventory but if you change your build and want these items back you have a means of doing this. If you want to change it up a bit you could make the item disappear from the shop after a random amount of time and then you'd need to find it at someone else's shop (someone else bought it but has put it up for sale at their shop now) Just some ideas. Thanks!