Instead of allowing managers to bid up their own players, why doesn't BB just add a Cancel Listing option on the Player screen? Then no one is getting tricked into bidding against the manager of the player.
In the real world, bidding on your own auctions is called Shill Bidding. Here is an explanation of what that means:
http://en.wikipedia.org/wiki/Shill. It is illegal under federal law.
If the only downside to shill bidding is that you pay a small tax when you have the potential to make big money, why wouldn't players do it?
It would be far getter to just add a Cancel button for auctions. Then, if you screwed up, you cancel the auction, you pay the tax (as a penalty for cancelling), and you get your player off the transfer list and no one gets hurt.