Cant beat the "MV-50" superflow sold at Pep Boys for $60.
Here's a write up on how to port the head and make it work even better. After the mod, it will fill a single 33" tire from 18psi to 35psi in just over two minutes.
http://www.4x4wire.com/index.php?opt...ects&Itemid=83
I've got 2 that I plan on running together with a 5 gallon tank.