Well, I paint 1/35th scale german armor and am using theTamiya Sprayworks HG brush, which is an Iwata clone. IIt does the finest lines I need for both WWII German and modern Nato armor.
I do not know which Tamiya and Iwata models are equivalent, but there is a comparison over on Missing Links.
I recently switched to a CO2 tank setup and am VERY happy with it.
It is silent, dry, has absolutely constant pressure, no need for a water trap and no oil in the lines like some piston compressors get as they age.
I got a big tank 20lb size (about a scuba tank) and a double guage regulator and spent about US$ 175, but a smaller tank or a used tank and a single guage regulator would be much less.
As for the airbrush, I am a member of the VLS 'mastersgroup' (nothing masterful about me, just their members discount buying club name) I get the membership as a b-day gift, but it runs about US$75. Then you get free shipping, 28% discount, free cataloges and updates.And best yet, a holiday time sale at 40% off!
My Tamiya airbrush +adaptor to Badger hoses was about US$100.
So, while this does not really stay within your pricerange, I figure I have a lifetime setup w/o many of the compressor hassles.
Might be worth thinking about.
Otherwise, sorry to waste your time (and bandwidth..)
Mike