No fighting words to be had as all that's beeing said here is true
The reason why i still love my old airbrush is because it has a larger needle and is greeat for large surface work like priming and base coats, also makes shooting metalics and anything textured way easier. I started with the badger 200 and upgraded and kept the old one that's all, i'm not saying you need 2 airbursh
Botttom line is all about how much you wanna pay, the only thing i'm going to add is....If it looks too good to be true, it probably is. The 20$ airbrush on Ebay often have cheap plastic parts that don't stand up really well with some paints or solvents.
Google revues before you buy, Youtube is a mine of information too!!
One of those will last you forever and is all you need to start especially if you're mostly building cars and you can probably get a set for around 80$. You can add a dual action later if you're looking for something more precise for detailing.
As far as compressors go you can get a table unit or if you have a "garage" type compressor that works to with the proper fittings.
I`d also consider picking up a ultrasonic cleaner sometime down trhe road, saves a lot of headache when cleaning time comes around!
Here's a series of videos from Dr.Cranky to help you get used to your new airbrush once you get it