I have brushed for 14/15 years and as a personal preference I would stay away from the Testors airbrush kits you find in the model/toy aisle at Wally World. They are single action and poorly made. Wont last or give you good performance, especially pushing thicker paints like you would like to do.
I would get an Iwata, Badger or Paasche. Dual Action meaning you can control airflow and paintflow instead of just on and off. More control means better detail. You dont have to break the bank on these either, you can score good deals on ebay or at your local art store. If you have Michaels Crafts stores in your area, keep and eye out for their 40% off coupons in the paper and get one.
If you have an air compressor, garage style for tires and power tools you can get an airbrush regulator for one of those instead of a dedicated airbrush compressor. The biggest thing with air compressor and brushes is constant air pressure. Using an airbrush on a normal air compressor will sometimes give pressure bumps in your painting and as the pressure in the tank goes down, your aibility to paint goes too. I have a dedicated airbrush compressor and you can get some incredible deals on ebay as well.
Probably more info than you wanted, but just thought I would give you some food for thought.