I've noticed of late, rather than people selling their stuff with a set asking for price, more and more are treating it like an auction.
While this is fair enough, it would be nice if there was a sub-folder in buy&sell for auctions of items, and perhaps some clearly defined rules to the process. (i.e. The first post must state an end time/date, all bids must be posted publically, etc..)
That way, it is easier to distinguish between normal 'for sale' and 'auctions'..