That's what I'm doing as well Ian.  My airbrush is going to be delivered tomorrow but I'm going to use some food coloring or ink to start off till I get the airbrush control and technique down a bit.  Then I'm going to get the basic colors of each Vallejo Model Air and Tamiya.  See which one I like the best and take it from there.  Vallejo I believe makes a 92 bottle set as well.  Ive seen that on evilbay previously in my searches.  I've found bottles of Vallejo Model Air for $2.39 the cheapest and Tamiya 23ml bottles for $2.28 so its pretty much the same price for the two best paints on the market.  Suposedely you don't have to think Badger Model Flex paint either so I'm eventually going to try some Badger paint out as well as I like to stay partial and bias to Badger when I can for the simple fact of support and sponsorship they give the SMA website.  Ive played with testors a bit recently so already know what that paints like and as of right now of course is what I use because it is what I have.  If you can find the paints somewhere cheaper, please relay the info to us so we can all utilize the cheaper prices ha ha.