Definitely not CAG. I've tried selling signed games there before, but everyone just wanted to low-ball the price. There were a few idiot teenagers there, PMing and harassing me on Ebay, too.
As to the OP: do you have any proof of authentication for the signatures?
From those pictures, it looks like you got the plastic hard case signed, and not the slipcover. That will affect how much your game will sell.
Interesting first post, by the way................