A few listing numbers would be helpful.
There may be shill bidding going on, but if the bidder is always winning, that's probably not the situation, since a shiller does NOT want to win. He wants YOU to win at the highest price you are willing to pay.
If the heavy bidder is making a lot of bid retractions, or if the seller is cancelling that bidders bids constantly, there may be collusion.
And you do know how proxy bidding works, right?
An item has an opening price of $5.
If you bid $10 , it opens to you at $5.
If I then bid $7, it is still yours but at $8.
If I then bid $100, I am winning at $9.
You can bid and bid and bid but until you bid $101, I will continue to win, even though I went on vacation and haven't looked at eBay for days.
Even then if sidthekid has an electronic snipe bid set to bid $200 at one second before the auction closes, he will win at $102. Even if he set up that snipe before you made your first bid.
High bid wins.
Bid once, bid your maximum and (usually) bid late.
