What about having a for sale section on this site? Put an item up on here for a limited amount of time, say 1 week, with the sellers desired price and then bidding goes on as usual. That way SOHCers get first crack at stuff and the seller can get what they want for it. If the part doesn't sell, list it on ebay. Sure, there is the potential that you could get more money for a part on ebay, but from an altruistic standpoint it could help out fellow forums members.
Not sure about all the logistics for this, but it's worth discussing.