Most of these things don't get expensive unless it's something very rare or game worn. I mean you can get a Witten autographed jersey for less than $300, Peyton's pretty much the only player that might cost a fortune, as far as the Vols go.
I have a autographed Fulmer and Manning football, Summitt and Bruce Pearl basketball. Manning SI covers and a couple of hats. My next big purchase is a Jordan autographed jersey, I've got magic and will get a Bird one as well but Jordan is the one I really want