Check out "pacific pinball museum" website, they've got a bunch of artists that have created murals for there expositions. They are awesome! top notch quality but not sure if for sale but they are artists that probably have studios etc.
Worth checking out! I was at there expo in 2012 in San Rafael, wall to wall posters, murals hanging from ceiling and not to mention 200+ pinball machines to play! Very well done show and artwork.