I was considering making listed art-pieces time limited. So after a 'seller' lists an art piece on there, collectors only have a limited time to collect it (may

I was considering making listed art-pieces time limited. So after a 'seller' lists an art piece on there, collectors only have a limited time to collect it (maybe 6 hours or so), after which they might need to buy it from a previous collector. Basically somewhat similar to your suggestion. If the site gains a bit of traction, I'll start working on it.