I think Bop Street probably has some, but most of their stuff is used, and they focus more on blues, jazz, rock, and other stuff. You could probobly find some good shit to sample there though.

If you havent already, you might try J.A.M on 45th St in Wallingford, Orpheum on Broadway, Sonic Boom in Fremont...I'm brain farting on record stores right now...If I think of any more, I'll put 'em up here.