Totally agree with Savvy there incidentally, good drybrushing is generally more controllable than airbrushing for most people. I went to art and design college for four years and was trained how to use an airbrush, and I still rarely break one out for the average model. I tend to think that airbrushed models look like airbrushed models rather than the real thing a lot of the time. Skillful masking and a decent steady hand with a paintbrush blows airbrushing out of the water most of the time. Won't be using one on my Akula anyway, and even though that's at 1:350 scale, I bet you I can do it better with a paintbrush!
To be fair, one thing airbrushes are good for is late WW2 German aircraft and vehicle camouflage at 1:35 to 1:48th scale, that and things such as the temporary camo changes on Messerschmitt bf109s in the mid to late 1940s. If you intend to make a lot of that kind of stuff, it's probably worth having a decent double action one.
Chock