Get one when what you want to do requires it. Unless you need it they are too much of a PITA.
The only way to do airbrush is balls deep. I don’t mean expensive stuff is necessary, just that you have to commit to total understanding of the tools so you can not waste time being pissed off. A see a lot of people will buy an airbrush and never take it apart because they think they’ll break it, f*ck that. If you don’t want to completely strip the thing sometimes multiple times a day then you are doomed. Half stepping only results in gummed up equipment, terrible paint jobs, wasted paint, and misery. If you do things right you get good results and that more than powers you through the hassles. If you buy an airbrush uses it a lot as soon as possible. Embrace your f*ckups because that’s how you learn. Get to the point where mistakes don’t scare you because you can fix anything. That’s the comfort zone.
The Juaggu is almost totally AB, that’s why it only took 20 hours. The techniques used require it (look on YT for “Mig weathering chipping” or something like that). The Nightengale is ABed because the pieces are small and I needed to achieve that gloss with much thinner layers than rattle cans usually produce. The interiors of the Fiat and Alpine were AB but rattle can is really good for car bodies so that’s what was used there.