Miles, I don't know where you get your Tamiya, but if you are buying them from a LHS that has the "small" rack you should look at Tamiya's website. There may be a lot of colors you aren't aware of. Also, they have some interesting military colors that look good on cars and trucks if you follow up with TS-13.
Duplicolor is nice too. As T.J. said, you are limited to 1:1 colors that have been used in the last 7-10 years or so. Make sure you use primer under Duplicolor.
I hear you about the airbrush. I get very little bench time as it is and I would get even less done if I had to clean my airbrush as well. Oh well, maybe when I am retired.