I recently picked up a new airbrush and a small airbrush compressor. Man. Talk about a difference. This thing is like night and day from the old one. My old one was more along the lines of a spray gun than an actual airbrush.
My new airbrush is a dual action gun. This means that I can adjust the amount of paint that comes out as I use it by pulling lighter or harder on the handle. It uses a TON less paint than the old gun. It has a much finer and smaller spray pattern but still gets great coverage - it just takes a bit longer.
One neat thing about this gun is that it has a little pot where you mix the paint instead of having to use a jar. This lets you mix up more paint as you go along saving even more paint. I know I keep talking about how much paint I am saving but I used to go through about half a bottle basecoating 10 marines. Now I use about a quarter of a bottle. Same for washes - a vehicle was a whole bottle and terrain was even more. I washed to large pieces of terrain and several smaller ones with one and a half bottles with this gun. Add in the cost of canned air and this thing will pay for itself in no time. If you are using canned air and a single action airbrush it is time to upgrade.
The compressor and airbrush that I picked up ran me about $80 total so it was a steal and a half. Here is a link to it over on amazon. As I have looked around online it looks like this was actually a pretty good value.