Well, despite being a lowly single action, I have been using with great success, a Passche H for YEARS for many kinds of airbrush jobs. It has THREE different needle sizes to choose from, 1,3,5, 1 being smallest. I like it because the airbrush itself as well as the parts are reasonably priced, it is easy to get replacement parts for it, easy to clean, and you know the company will be around tomorrow. Of course, any airbrush is only as good as the compressor you are using. I have a Silent Air 30. A little pricey but worth every penny. I have more expensive airbrushes, like an Iwata HP-C for very fine work, but the Passche H is a workhorse and has never let me down.
BTW, you can likely find a good deal on a Passche H(or others) on EBAY. I see a LOT of airbrush equipment up for auction there. I seems a lot of folks buy them thinking it is the airbrush alone that makes you a an airbrush artist. When they learn the truth, the stuff goes up for sale! Take advantage of it.
If you still insist on a double action, I might suggest looking at Iwata product.
MJB