There is an international statute that the major auction houses 'adhere to'. It prohibits the use of either the vendor bidding on his own material or employing a shill to do so. I used to get Sotheby's catalogs free and major ones had the rules reproduced within them. Not sure if I have any now, I stopped getting them when they started charging for them I may still have the Princess Diana New York dress sale catalog somewhere.

Now, that said, ths does not mean it dont happen Ive witnessed it. I used to help as an auction agent (proxy bidder) and probably attended near 100 auctions worldwide and saw plent underhand goings on

Still, fact is, its generally regarded that shill bidding is unacceptable. Im sure this is why ebay follows (or says they follow) the same principle. After all, why would they care, the higher the price the more the fee.

Maybe ebay covers some country somewhere where shill bidding is a criminal offence punishable by castration