I used to use syringes but found all sorts of down sides to them. Then I was visiting my dad in the hospital a few years back and saw them dispense his meds in a small graduated cup. I convinced the nurse to give me a few and they are PERFECT. The measurement markings are small enough that you can mix small batches of paint accurately, but they are big enough to mix enough paint for base coats on large kits in one batch. I get mine at a local medical supply store for a couple bucks for a 100, but I have found them online as well http://www.myamericanmedical.com/products/non-sterile-graduated-plastic-medicine-cups.html
This makes them very affordable and completely disposable... no more trying to clean out syringes!
The one hint I will give you is that when mixing paint in them, use an old paint brush. I was using toothpicks and the like, but found they wanted to flick paint out of the cup. I found an old, cheap craft paint brush lying around and now it is my dedicated paint stirring brush. The paint mixes better and I'm not flicking it all over the place.
As a side note, I've switched back to enamels myself, and I am having great results with a much thinner ratio for my paint... 1.5 or 2 to 1 (paint to thinner). I can spray at a lower pressure and I'm getting better results that way. It works for me at least.