I don't think there is anything ethically wrong with it. As long as you're not shilling and would be willing to pay if you win, then bid away. Think of it this way: if you really want one, this guy is going to make you pay. Nothing wrong with returning the favor.
Banner by mattfastiggi
Collecting: Brett Favre (7,771 unique as of 6/1/2015), Packers, UW Huskies (Shaq Thompson, Shelton, Peters, Kikaha, Sankey, ASJ, Trufant, Locker, Brunell, Dillon, etc.)