for about $99 on Badgers site you can get a reconditioned Thayer and Chndler AirStar V which is very quiet and perfectly suited to modeling.
http://www.badger-airbrush.com/garagesale.htm
of you can go the other route with the 2gal Campbell Hausefield for about 60 or 70 dollar from the local hardware store/wal mart. either one will do the job, the thayer and chandler just a lot quieter. no real difference in quality of painting etc...
Personally I have the construction grade one, but am looking for the opportunity to switch over to the other type as the noise reduction would be nice.
if you do opt for the campbell hausefield type you will need a moisture trap for about $20.00 fromt he same place you got it at, and a 1/4" NPT nipple to screw the airbrush hose onto. In addition, the regulator gauge on the compressor has markings in increments of 4 or so PSI, a hobby regulator has markings in 1psi increments so it's easier to be more precise in your pressures. it's not a necessity but it will certainly help you!! again thats about $20 online, or at Hobby Lobby or Michaels and the like...