I have several air brushes, Paache VL x2, two Iwata, one siphon feed and one gravity, and I can tell you the best bang for the buck is this set. https://www.amazon.com/Wakrays-Master-Airbrush-Professional-System/dp/B01JISBYN6/ref=lp_8090750011_1_25?s=arts-crafts&ie=UTF8&qid=1488268594&sr=1-25-spons&psc=1
I have two of them, and the features and extras for 30 bucks make it easily the best money. They aren't as smooth as the Iwata, but they spray just as well, and only take a little more maintenance than the Iwata.