He buys using other usernames too. When people start following him and outbidding him he'll do that. I used to do that to him and he'd use a different bidder name to try to throw me off the item.
Sam bought a receiver from me and I blocked him from then on. A couple years ago a newer GB user bought something from me, but a couple months later I saw in Sam's feedback that the same guy bought one of the over-priced fakes, plus was bidding on another item. So I looked his email up and contacted him to tell him all the reproduction parts on it. He didn't respond and won the high priced fake anyway. Perhaps it was a buy for someone else. Perhaps it was one of the shill accounts to bid his own items up and he used that account to buy something from me because I blocked him..