Got rejected by TechStars again, but we're getting better at it
badcheese.com
badcheese.com
I know the critical mass issues makes challenging eBay/Craigslist rather difficult, and probably turns off investors... But, I think there's room for a new, much improved bidding platform.
I think this a great idea. Have you thought about trying to partner with other ad networks as a quick way to get access to content publishers? That could go a long way toward solving the chicken/egg problem of how to attract sellers to your marketplace.