That's the Tri-Star show in Houston. Tri-Star will be selling pictures at the show as will numerous venders. You should be able to find what you are looking forward. You can also get a picture of you together and then let him sign the picture.
Berkman is hilarious. He uses the "Puma" nickname because he didn't really like the "Fat Elvis" nickname. Of course, he will add "Fat Elvis" behind his signature if you ask. He is a good guy.