if i am not mistaken MLB controls a lot of those rights... on cape cod we have one of the best summer baseball leagues in the country. a lot of these college kids have gone on to the majors.. the league as a whole pays MLB a fee for the rights to use the team name and logo... it is funny in some ways for MLB may contribute thousands of dollars to the league, then turn around and ask for fees to allow the teams to use MLB logos...
try MLB web site for some team logos you might be able to work with......