Carlos Beltran's trade value depends on how he finishes the 2010 season. If the mets don't have the money to spend, they should look to dump some salary. Not saying these teams will take it. It's just an idea.
The Boston Redsox don't seem like a bad idea since they are a big market team and are always looking to improve to over take the yankees. How about the mets getting Ellsbury and maybe Okajima. I would love to get Bard, but I don't see Boston parting ways with him. Beltran would be the Redsox Center fielder, but boston would have to do something with Cameron. Ellsbury is a perfect fit in center field for the mets. He would also be a great number 1 or 2 batter. He's a guy would could bat .290 and steal 60 to 70 bases with a run happy mets team. Okajima hasn't been as good as he was when he first broke into the majors. But it's worth a shot. The mets bullpen can't get any worse than it is now anyway.
San Francisco Giants - They need a big bat in that lineup. I don't know if they would be willing to part with Cain. But the mets should offer a sweet package to bring him to new york. He would be a solid number 2 starter behind Santana. This could also give the Mets a chance to sign Crawford.
Like I said, these are just ideas. But this team needs a big change and out of the mets star players, i don't see any other getting traded besides Beltran.