You can thin Rustoleum Gloss Protective Enamel with acetone and brush it on*, for way cheap. Thanks to the quick drying time of the acetone, it is a snap to achieve a "paint brush streak" patina using this method that is practically impossible to achieve with a spray gun, even if you do stoop to using women's underwear in the painting process.
* This is for the Banshee from Randy Powell. I covered the wings in red Monocoat because that's what I had. I was showing it off to my RC club and got the comment "but that tail is an ugly color of red" (it looks like it covered with red tissue, then faded thoroughly in the sun). Claiming just working on it enough to make it fly nice didn't, well, fly. So now that tail is an attractive color of red, with its distinctive patina.