An ebay auction is open to the world. I am colluding with 1 or 2 people.

The bottom line is when the top 2 bidders bid $100 to $200 more then the 3rd high bidder (when the winning bid is only $200 to $300), it only makes sense to stop banging heads on auctions we are both interested in. One of us is still usually the winning bidder. I have, in no way, estopped bidders #3 to infinity from bidding higher.

This may come as a surprise to you but such a practice is done by many if not most of the high end bidders.