I dont think anydoby can built an auction site like eBay. Does eBay have any patent like rights with auctioning sites???
That would be quite impossible. The idea of auctions isn't new so they only thing they could possibly patent is their code. But given you can't even get hold of that you're perfectly fine to make your own. Given that you come up with your own name and layout. If you called your site eBuy you might get into trouble but otherwise you will be fine.