WizKids has announced that it will release MLB SportsClix Extra Bases, the first expansion for its SportsClix CMG, in September.  The set will contain 104 MLB baseball players, with choices similar to those made for update trading card sets:  players that haven't previously appeared, hot rookies, and players in new uniforms (such as, we assume, A-Rod in pinstripes).  Each Extra Bases booster will contain three figures at $6.99.