A half glance at the samples and the first thought that popped into my head was 'nope, not my thing'. The second thought was screaming AIRBRUSH! Have you tried any airbrush artists in your area? Someone that's been doing airbrush work for a few years could probably turn them out in a jiffy.
I'm a bit envious of the professional airbrush crowd, those people definitely have some skills.
Then again, have you thought about making a thin 3D contour mask for each color and painting them in-house?
BTW, what, exactly, is your avatar?
Just my 2 cents,