Whereas it is a nice gesture to sell these at your cost, I still voted "auction". I tend to think that if you list all your chips at cost (in groups or individually), your higher demand chips will get snapped up quickly (especially if its under market), and, depending on how much you bought (or list) the lower demand chips, you may be stuck with these or need to lower your price to move them. Its the classic limit your upside but not your downside scenario. By an auction, you may at least have the possibility to use gains to cover loses. If you do decide to go the fixed price route, another way to mitigate this issue is to group high demand chips with some of the lower demand chips, but that would be a little tricky to figure out. Good luck!