I took Bob for a Pokemon guy, guess I was wrong.The only thing I can think is to call ahead. The sale doesn't start until tomorrow though.
It's a low-ball offer, but if you'd be interested in selling just the Gnarly Tree Rex for $20/shipped and save the effort of trying to resell it, I'd be willing. You'd totally get more if you shopped around (and removing him from the "bundle" greatly reduces the value of the rest of the game for resell). Just FYI.