B2B Website

I would require a B2B website, more like <[login to view URL]> where people could come over and browse for used/new items and could exchange them for the items that they currently hold. For eg - Person A has a wrist watch. he could put that on the portal. Person B proposes to offer an iPod Shuffle in exchange of this wrist watch Person C proposes to offer a pair of sunglasses in exchange for this wrist watch. Now Person A has a choice to choose and accept the offers from either B or C. So the deal gets finalized between the two parties and both the parties are notified of the deal. Thats almost it what I need. The responsibilities of approaching the either parties rest with the users of the site. The two parties would be provided with the email IDs of each other in a mail that would inform them of the finalization of deal. This is a very prelim concept that I have in mind. I would also like to hear the thoughts of the coders on this. And I would prefer an ASP.NET solution for this. Thanks Ashutosh