All of the recommendations given are spot on point, you guys nailed it. I strongly second the sentiment to do a throrough search, spend some time at Don's Airbrush website, have a good look at Snib's as well. Youtube offers some very worthwhile reviews, with accurate information, also the actual airbrushing process, basic to advanced.
My first airbrush was DEFINATELY not my last, I'd say the chances of you finding the absolute best choice for you on the first purchase, about 5%. So I recommend looking for and buying an AB of good quality, but avoid the temptation to go for the very top ones that are really expensive. The old adage applies well, gotta learn to walk before you can run.
Old Goat could not be more right, learn to use it and even more important, get to know the inner workings very well. An AB not sufficiently cleaned and improperly adjusted, leads to some real grief and major dis-appointment, guaranteed to be a boat load of frustration.
Over the years, (50+) I have owned many AB's, Iwata, Badger, Binks, Paasche and others, single and dual action, external and internal mix. Pretty much covered the field. I have developed enough experience and knowledge to understand what works best, to suit my particular needs.
With some time spent searching, you can find outstanding AB values at the factory authorized discount dealers, Wyn Wyn, Chicago Airbrush and TCP I have dealt with many times, have had completely satisfactory purchases with them. Often you'll find discount coupons at special times, usually about 10-15% off the usual price. An AB is a critically important tool for a hobbyist, so I recommend buying new, among other things for the warranty. For the record, I have only had to send an AB back once for warranty replacement, but it can happen.
Following is just my entirely personal preference, based on my experience. My painting needs now are served perfectly by my Badger 100G, 200G, plain vanilla old 200, and Iwata HP-M1. I have several others still, but these are my go to AB's.
My 100G was purchased new on a coupon sale, around $50.00, just an outstanding value, considering the quality of spray it provides me. Can the $200-$300 AB's out perform it? In the hands of the right person, sure. Do I need that performance level? Nope, wasted on me.
That is why I recommend against ever buying more AB than you will really need, and especially so when you're just beginning. If you stick with airbrushing for the long term, over time you'll learn what you actually do require, then you can refine your search to the certain type and performance level that is best suited for you.
The compressed air source is an entirely separate issue, you will find some that will work OK for not much money, others that are very quiet, plenty of pressure, etc. for more like $150-200. I only recommend no canned air, poor choice. A regulator and water trap are other items to consider, but your search will determine what you need.
I wish you good luck in your search, hope you get hooked up well and cost effectively.
Patrick