I quite like this idea because a lot of the preparation for that could be done on the forums before the event ...let me think how best to work it.....what about a used marker stand for the guys on here, you can set a sale price with a reserve price if you wish if the price offered is above reserve its sold.
maybe a list could be put on here of the gear that will be at the event, but obviously all deals would have too be in cash too save any headaches