Could you ask folks posting "Group Buy" offers to put either a begin/end date for orders in their thread title (i.e., Road Frame - 01/01/09 through 03/31/09) or modify the title to highlight when orders are open/closed (i.e., Road Frame - Orders open through 3/31/09, followed by Road Frame - Orders now closed)?

I drop by now and again, often after seeing the "new posts" flag, but often find no new group buys...just folks talking about delivery dates and/or first experiences with the merchandise.

Just a thought.