Hi, Alvinhy -
Over the years I've owned many of the popular airbrushes, Paasche, Badger and the Neo bottle feed. So many good ones, but for reasonable cost, spray quality and long component life, I have selected Badger as my current everyday, all around brushes. My personal favorite and most used is the 100G small cup, also using the 155 Anthem medium and small head/needles, and the 200NH for large area spraying, like the overall base coat of a model.
The 100G comes in large and small cup sizes, either works well, I find the large cup size to be a bit top heavy feeling, but it will cover a much larger area with a single loading. I find that a very small amount of properly thinned paint goes a very long way, so for me the 100G small cup works perfectly.
The large cup is a bit harder to see above or around when working close, so the smaller size does help with seeing what you're doing, it's also a bit lighter. With the smaller cup I run out of paint sooner, yes, but that gives me the chance to run a thinner load through to clean up the ports and cavities, between paint loads. If you can live with the smaller cup size it makes a fine airbrush, otherwise go for the larger size. I can paint about half of a 1:72 model plane, with one small cup load.
My newest airbrushes were purchased either at my LHS, or at Web airbrush, Dixie Art, TCP Global and Chicago Airbrush. A friend recommends Coast Airbrush as a good source, but I haven't tried them, All were good prices and quick delivery, I just check for who offers the better price. I do suggest avoiding the liquidators and pawn dealers, maybe OK, maybe not.
Once again I highly recommend a look at Don's Airbrush Tips, type it in on Google and you'll see plenty of detailed info and comparisons of types, it was of great help to me, I learned a lot.
For about forty years I used exclusively Paasche, wonderful tools then, but sadly the last few parts orders and airbrushes as gifts to friends were delivered with quality issues, mostly could be fixed, but should not have been delivered that way.
If you try Webair, tell them it's a Badger referral and you get a 33% discount, the other large dealers sell for a roughly similar amount. Some even have free shipping, which does make a difference. Check around, it's worth the time.
Good luck with the search, if you hook up with an airbrush you like, you'll have some real fun.
Patrick