i'm pretty sure halftones would be your best bet for your design. Although i dont believe you can to that on a black tee with out a white base so that would be five colors.
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I Run An Epson 1400 with and ALL Black CIS system and it WORKS!
As jsf said, 3 color halftones with white underbase. Use light purple, yellow and teal as your primary colors. Make sure you separate the artwork correctly so that light purple and yellow make the in-between colors as well as the teal and yellow to make that aqua green color.
does anyone think that a blend swipe would work? i don't have a lot of experience with it....and i need to print a couple hundred shirts that way- so i am not sure if it is feasible....
You could do it as a white underbase p/f/p/f
then do a blend. However, a lot depends on what your customer thinks about them being different from each other........and getting some muddying.....
I dunno...doing a couple hundred, that would be a major headache as a fade.
I'd do halftones, simulated process.
help printing a gradient 
