I grew up going to farm auctions, mostly equipment and livestock. If a seller was caught bidding on his own equipment or livestock, he was ejected from the sale, along with whatever he had brought to sell. There was no such thing as 'buying back' your own stuff. If it didn't bring the price you wanted, you "PO'ed" it and took it back home.
Damn right.
You want to see the prices at an auction plummet?
Make it known that the owner is bidding you up.
