Any status of this? I too am in need of one but not until the fall. It's a long way off still but I have an idea mapped out and if there isn't one ready by then I'll be doing my own auction open source project come Octoberish.
Mine will be provider based so to be customizable and be more focused on bidding on user roles rather than products. Although I think my provider will allow any type item to be auctioned.
So I would create an abstract auction item interface that my auction engine interacts with to get all the properties for an auction item. Then, you can select from 3 separate types which all implement this auction item. A user role ID, a custom auction item or a provider interface for an auction item.
It will be a similar type design as my hopefully to get wrapped up open source newsletter project at the link below. This is one reason I'm interested in doing my own as I have experience with something similar.
http://forums.asp.net/thread/1051836.aspx
Jason