Evan, I've used, and still use, a "cheap" airbrush for general work, and they've been fine.
But I bought a Harder &: Steinbeck "Duo Ultra" a while back, and it's been brilliant.
The "Duo" boxing comes with two needles, tips and paint cups, and doesn't "break the bank" cost wise. I got mine from "Everything Airbrush" in S.E. England, a company I've used for a number of years, and their service, and pricing,, is excellent.
I've managed to do some extremely fine-line work with it, albeit in 1/48th scale mainly, but for standard "wave pattern" RAF / RNZAF cammo in 1/72nd scale, and probably Luftwaffe mottle too, i think it should handle it.
I did a review when i bought the 'brush, which can be found here on the forum in the Modelling threads.
If you want / need more info, give me a shout or PM.