You might want to look at the Passche Ra75.
It's a regulator, with gauge, and moisture trap all in one, and it's designed to be used with airbrushes, not air tools, all for $27.95.
The gauge is calibrated in 1psi increments, with a maximum pressure of 60psi.
See link below:
http://www.dixieart.com/MiscAccessories.html#anchor89730
I bought one late last year, and now I couldn't live without it.
Karl