Here's part of my airbrush ritual...I have 3 Iwatas btw and I absolutely love 'em.
I only spray acrylics because of my wife's asthma, and I was running through quarts of thinner and cleaner.
I went to the local auto-parts and bought 2 gallons of windshield washer fluid, I think I paid about $2 a gallon. I then bought a package of furnace filter elements (another $2) and stuffed one (I think there's 6 to a pack) into a 2 liter soda bottle (the plastic type).
I cut a hole in the top of the bottle and covered it with tape. When it's time to clean the airbrush, I run lots of windshield washer fluid through it, sprayed into the soda bottle. This prevents the stuff from going everywhere and messing up my spray booth.
I've found the windshield washer fluid really works well. Final step is to go to a department store and find a small ultrasonic cleaner...they're usually in the toothbrush area...used to clean dentures. I paid $30 for mine...if I've used the brush heavily, I drop it into the ultrasonic cleaner overnight and let it soak in windsheild washer fluid. Comes out perfectly clean the next day.
Jeff