Hi!,
I bought an airbrush a couple of years ago, got trained to use it and now use it all the time. Most clients of mine like the fancy french but when it comes to school proms and parties etc, I get asked for all sorts of things! I recently did green and yellow with black palm trees for a local african artist who had an exhibition near me!lol.
If you do go ahead...definitely get a compressor. I have tried with cans, especially with the body art and i found the pressure was crap and they didn't last.
Maybe find out from your existing clients if it is something they would like? Urban geek is right, Theres no point in investing a lot of time or money if you don't think it would sell. I have an example board up and that creates interest.
A lot of my clients like airbrush designs on their toes too in the summer!!
Sam xx