And don't forget the rules....Excellent idea. I've seen this on other forums before and will quickly add that whatever you decide to offer must be of equivalent value and condition (or greater if you're a generous sort). There's always one who grabs the gold and gives the tin..... no grabbing this nice headband and offering 4 mucky pods, 2 of which have broken lids.
when an item sits for a day or two generally it's the quiet and polite way of telling you that you're offering a pile of sh*te, so add something or change it.