Whats the Value of an NFL Contract?

Hey guys, I have a couple of authentic NFL players contracts. I have never seen these discussed and am curious to find out more.

The first is an original Steve Young contract when he was with Tampa Bay in 1985-86. It includes his salary info for that year and is signed by him.

The other is a Troy Aikman contract with the Cowboys for the 1994-95 season...but this one is cool because it includes an attached sheet that includes incentives and bonus' based on him reaching certain on-field accomplishments (making the Pro-Bowl, touchdown passes, etc.) The Aikman contract is signed twice by him, once on the contract and once on the bonus sheet, and is also signed by Jerry Jones, owner of the Cowboys.

Does anyone know what kind of interest is out there for such unique items? Thanks. -stefan