
Hi Dave, welcome to Armorama
As Martin says, an airbrush is a very personal thing, what one likes another wont. I also agree that it's a good idea to get you "feet wet" with a cheap airbrush, but I wouldn't recommend the likes of the very cheap ones, those that come on a card back with blister front. You can get a decent single action airbrush from the likes of Tool Mart (I think it is) or Screw Fix, for about £25.00 which is similar, but not as good as the Badger 200. I used the Badger 200 for about 20 odd years until I switched to a Double action 2 years ago.
In some ways it depends on what you build. If you only ever build subjects that only require hard edge masking then a cheap airbrush is all you will ever need. If you require to be able to paint free hand soft edge (or even hardish edge camo) then you will need a better and therefore more expensive airbrush. If you buy the £25.00 one, I mentioned, it won't go to waste if, later, you want to upgrade as it can be used for applying varnish and the like. This is what I use my old Badger 200 for now. My new airbrush cost £160.00 but you don't need to spend anything like that. You will also need a compressor with holding tank, moisture trap and regulator (canned air is not a good investment). For a first compressor I would look for a second hand one, even a simple diaphragm compressor, without a tank is useful (I used one with my Badger, until it finally gave up). I can give you a tip of how to get away without a tank

if you should need it. My new compressor would cost £800.00 new but I got it for nowt

but a decent, new compressor can be, relatively expensive, so go the second hand route to begin with.
Before purchasing my new airbrush I spent about 6 months on research. I would suggest going along to art and graphic shops and ask to look at what they have. Talk to the people there, most of them won't know a thing about airbrushing, but you may pick up some good info (if everyone you talk to gives you the same snippet of info then that’s probably about right). Remember though that they will be trying to sell you the airbrush make, or makes, which they sell.
Above all get to feel the airbrush, how does it feel in the hand, how is the trigger action. Ask about how it strips down A lot of people give up on airbrushing, probably blaming the airbrush. Probably the best 2 pieces of advice I could give you is that if it ain’t working it's you not the airbrush. Keep it clean and it will do what it is supposed to do. Get to know the paint and how it likes to be treated.
More on all this when you have made your choice.
Mal