This guy isn't really asking for much is he? He not only wants someone to build a "better" clone of Amazon but also; auctions, classifieds, forums and a freelance jobs section on-top of what would be an extremely complicated project not-to-mention expensive. I bet the winner of this project will just skin a copy of Magento and install a couple of plugins in unison with a bot script that would scrape all of Amazon's categories and add them. Good luck to the guy, I hope his pockets are deep.

Wouldn't surprise me if the project ends in a skinned copy of Wordpress with WP-Ecommerce installed for the store functionality, haha.