Take the jump and get one, once you have mastered it you'll never look back!
If you do decide to get one, buy a double action airbrush with an assortment of needles. The Badger 360 (With built in cup) is my recommended choice, as the cup rotates 360degrees, so it can be used as a bottom feeder for attaching the glass jars, or rotate it to the top for fine detail work. Then there is the Badger 150 box set with fine, medium, large needles and don't waste your time with air cannisters (The pressure is never constant and they don't last five minutes!..not to mention expensive.) Buy a well known compressor like Sil-Air, Revell, try to get one with a reserve tank, moisture trap, adjustable psi, and if your going to be using it alot, then make sure it's silent running (The above makes usualy are.) You can buy how to books on airbrushing by Badger, but the instructions you get with all Badger airbrushes should give you a start.
I use my equipment every day as i'm a proffesional model sprayer, i spray 00 Gauge trains for a living. The equipment i use is a Sil-Air Compressor, 2X Badger 150's, 1X Badger 360.