Guys, there's nothing criminal or illegal about agreeing amongst yourselves how to (or not) bid on an auction. Similarly, there's no civil law claim or violation either (no tortious interference with contract, for example). Ebay may have bidders guidelines that they issue, but ebay is certainly not the law. The worst that could happen is ebay could perhaps ban you from their website but I'd think that's highly unlikely.
Here's an example of auction hanky panky that is significant (in contrast to the above, which is insignificant) and similarly not illegal: the big auction houses such as Barrett Jackson regularly "salt" their auctions by running through cars that the auction house either owns or are borrowing then bidding on their own cars up to crazy high prices for the purpose of creating the appearance of selling frenzy and high prices. Now, in my estimation, that's just outright deception and used car dealer bs at its absolute worst, but, it's not illegal nor is there a civil violation. It's just plain wrong, however, that's vastly different than a couple of guys agreeing not to bid against eachother on a $299 item....