I prefer automotive grades paints to hobby store paints, personally. I have used just about every brand of RC/lexan paint on the market, and the only one that compares to what I use full time is Spax Stix, and it's still quite lacking. Water based paints are safer for the user, but don't create a true bond to lexan.

Another quick lesson that you found anywhere else on RC forums... don't use soap to wash your bodies out. Anything that is safe for momma's hands in the dish water is guaranteed to leave an oily residue behind. This doesn't mean that you're going to see it, or even notice it's there, but this comprises durability, and adhesion. 70% alcohol that you find at wal-mart or any store, is the best option if you don't have proper surface prep cleaners. Use a terry towel or something similar to whip on the alcohol, then hit it again with a dry lint free rag to whip it out. No soap, no water.

You can use any lacquer based paints on Lexan, you just have to prep the surface properly, and use and adhesion promoter. Honestly... all paints that go on lexan should have an adhesion promoter. This would eliminate the need for steel wool all together too.

To back your paints, you should be using some sort of protectant... another various color won't last any longer than the paint you applied for looks. If you're looking for a cheap alternative, Rust-O-leum crystal clear enamel is the only way to go... many pro painters use this, and I did for a long time. I've since switch my entire line to automotive grade products, and the durability is much great than any RC brand paint or backer. But when you're looking to paint something up quick, and just put some color to your ride, RC grade paints are fine!

Hope this helps!
Adam