>>105659410
An airbrush is a serious investment of money, time, and effort. It needs significant infrastructure to use effectively (good compressor, ultrasonic cleaner, cleaning mix, special paints, mixing bottles, etc.) some of which is difficult to cut costs on. Saving a few bucks on the airbrush itself isn't going to make a huge difference and could cause a lot of headaches.
If you don't want to spend a lot of money, I would recommend not bothering with an airbrush and instead just spending the time you would use learning airbrush skills on getting good with drybrushing and sponging instead.