For cleaner, I buy my Testors Acryl cleaner directly from Testors -- thru their Web Site. Look under Airbrush Accesories to find 32oz of Concentrated cleaner for $10 (plus about $4-5 shipping). I mix it with 2 parts water to make 3 quarts! That's far better than the $5 for 4oz hobby stores charge!
This is WAY better than just water... and I think a bit better than Isopropanol... if only for the smell.
Isolropanol works well too... but I tend to like using what's made for it. Water will "work"... but just in a pinch. I avoid it!!!!!
As too thinners... the alcohol works, but again... I stick with the manufacturers stuff when I can.
www.naplak.com/modeling ... a free site for modelers
www.scalehobby.com/forum/index.php ... a nice Modeling Forum