You can get air brushes cheaper and some are okay. My first airbrush was £45. However I killed it spraying cellulose paint as it melted the rubber seals.
Better quality air brushes use ceramic seals.
If you have a compressor already and is suitable that will remove a lot of the cost. Compressors are typically £40 – £100 to buy (pro ones £300+).

When I first started airbrushing I was a little disappointed as my initial attempts were worse than hairy stick painting.
There’s also the time to mask everything for spraying, then re-masking, then re-spraying, re-masking etc.
You’ll need a mask, maybe a spray booth to extract all the overspray and fumes.
The extra effort is definitely worth it though.