airbrushing can be cheap or expensive, depending on the way you go about it, i have a dual action sprayer with 4 different nozzles, acrylics and enamels use different nozzles(don't have too but the end result is much better.
have done many traditional and true flame jobs, abstract, scenery and water murals on cars, fridges and welding masks. but never got into the wizards and death theme.
many hobby shops sell starter kits, don't waste your time with the cheapies that come with a can of propellant, get a compressor and at least a half decent brush.
single action brushes just have basically a valve for the air, some on or off and some are touch sensitive, push harder- more air, softer- less.
double action brushes generally have a sliding trigger. same air operation as a single action (harder-more,softer-less) but the trigger also slides back and forth- fully forward and you get no paint, slide it back and out comes the paint, further you go the more you get.
double actions are alot better when you've had a bit of practice but would recommend starting with a single first just to get the idea of how to shade, layer, build and highlight.