Everyone around me has air compressors, I have 2. The airbrush I use is a $20 harbor freight and a $80 Paasche vl.
As for casual hobbyist painting a few bodies a year, you didn't mention if it's 1/24 or 1/5. Alot of variables missing. The op asked what's cheaper, and I stared my experience...
Cheapest Is airbrush, and use the can to seal it when done. Dark colors first, light last. If you break that, silver prevents bleeding of darker colors into lighter ones.