Where are you guys gonna put Cameron? One of the reasons he's unhappy with the Mets is that they shifted him to right to make room for Beltran in center. You gonna move Damon to left and put Cameron in center? Or put Cameron in right until Nixon gets back? Cameron will not be a happy camper unless he goes back to center. You'd be better off trading for him in the off-season after Damon walks as a free agent
Probably get him cheaper than for Manny.
The only other guy the Mets have who'd be equal value for Manny is Cliff Floyd, and there's no way the Mets trade his relatively cheap contract to assume Manny's. Not for basically equal production offensively and wrose defense.