Apex,
I'm not a profesional bow builder (but I did stay in a Holiday Inn Express) but have built quite a few bows. Like you I decided I wanted to use spray finishes.
I had a small compressor (probably like yours) and a cheap Wal-Mart, Testors brand, air brush I had adapted to go on the compressor (about 2 bucks worth of plumbing stuff from the hardware store). I used it to paint bass poppers for flyfishing.
The only problem was the jars were too small to hold enough finish to do a whole bow. One day as I was cleaning the rig up I disscovered that the Testors brand paint thinner jars had the same size mouth as the small jars that came with the air brush, VIOLA more volume and enough finish to do a whole bow. I think I paid 10 or 15 dollars for the air brush set.
I do thin my finish and put on light coats (no runs, drips or errors so to speak). I generally do 3 coats of high gloss, then a coat of satin to get a no-shine finish.
Like I said, I'm no pro, but this works for me.
Another option is to head to the pawn shop the weekend after payday and see what was hocked the week before and never claimed. I have found lots of good tools and stuff this way.
OkKeith