For brushing I have much better results with acrylics, as opposed to enamels. For me, Tamiya acrylics do NOT brush well. Vallejo Model Color acrylic does produce results I'm quite happy with, thinned or straight from the bottle. For brushing acrylics, keeping the brush faultlessly clean as you progress is critical. I use lacquer thinner for cleaning as I go, then a final cleaning with acetone before I put the brush away. A thorough, quick rinse and towel dry about every three or four brush loads, ensures no little naughty bits getting into your finish. Be careful to avoid breathing acetone vapors, or any others for that matter.
Apartment dwelling and a noisy diaphragm compressor, may not make for some happy neighbors. Schucks Auto had a Sunday coupon sale, I bought a Coleman for my garage use, 1.5gal. tank, regulator, gauges, water trap and drain valve included, $30.00. It's LOUD! There are quieter ones, check it out first.
Airbrush: Over the holidays I used a Chicago Airbrush coupon code, scored a new Badger 200G, well under $38.00 including shipping. The really cheap knockoff Chinese jobs from places like Harbor freight can actually be OK, (if you get a good one,) or terrible, (if you don't.) Taking your time can reward you with an outstanding airbrush buy, I could not be happier with my Badgers. With careful use and good maintenance, a quality airbrush can give many years of trouble free painting.
Good luck with your search.
Patrick