You can get may different brands and types of air brushes that are ver affordable. Even Harbor Freight has a cheap little set that is only a few dollars that could get you started. Airbrushing is always going to be the best bet for modelling painting so if you plan on any future projects you really want to look into it some more. Paasche and Iwata make very good brushes and have very affordable sets. You can even by canned air for them bet I recommend buying a dedicated compressor.
As far as your tank , you really want to use a good self etching primer first. any good automotive primer will do and you can use the rattle can for that. if your going to use one solid color the spray bomb will work for that too. But, if your going for a camo or pattern type then an airbrush is almost required. Look up Chicago Airbrush. That site has everything you could possibly need and very good prices also.