the question is what is he worth....
Exactly, Hache.
This is a three part question:
Is he an upgrade over what you have at the positon? If you're Buffalo or San Fran then the answer is a resounding YES!
What's it going to cost you to get him? If it's a fifth round pick, he's a steal. If it's multiple #1's, then the answer is no.
What are you going to have to pay him? He certainly not worth Peyton money but for the right price you'd have to take a look (if he would be an upgrade and the cost to obtain him wasn't prohibitive).
Doc