I was in Costco the other day and they had a MasterFlow MF-1052 compressor for $60 or so. Went online to make sure it was the right one, and I'm going back to pick one up. I've been wanting onboard air ever since JP started this thread
Here's a pretty good thread on the MV50, MF1050, MF1052 compressor family. It kinda rambles but has some good info
http://www.yotatech.com/showthread.php?t=64004