I found an excellent and inexpensive airbrush cleaning solution (for acrylic paints). The link is however here are the ingredients:

Distilled water - 3 parts
Window cleaner ("Windex" or equiv. with ammonia) - 2 parts
Isopropyl alcohol 91% - 1 part
Glycerin 1 drops for each 15ml of water

In my case I used a 60ml plastic jar as follows:
Filled with the water to 30ml
Added window cleaner to 50ml
Added alcohol to 60ml
Added 4 drops glycerin

Works great on slightly dried (several minutes) paint, much better than acrylic thinner. Will not remove time dried paint.

Lew