I'll give you an example of what happening in one shill bidding episode.

A rack of a certain type chip was bought by a well known seller. He happened to pay $30 per chip. Most of the collectors of this type chip saw the auction and knew who bought it. I, myself, would have paid $50 to $60 per chip for a set of 3. Knowing the owner paid $30, I thought my price was reasonable.

Now for what happens with shill bidding. Eventually the owner put one of each chip on ebay. One particular collector (a very nice person), had more money than knowledge. By the time the shill bidding ended, he wound up paying $800+ for the 3 chips. If you removed the 2 shill bidders, he would have paid $180.

BTW, the seller uses the same shill bidders on EVERY auction he has. Needless to say, I and several other major collectors NEVER bid on his auctions no matter the price.