Mmmmm.....I live in Australia and Derivan is an Australian product part of the Matisse-Derivan range which make artists materials. Not affiliated, just like the printing inks. Have a look at the link to see if it might suit:
I keep a black and a basic colour set but I keep a big pot of the Extender because if necessary you can mix any colour acrylic paint into it and have that colour to print.
It's marketed to educational institutions so maybe through school suppliers in Canada or the US?? Or maybe similar type product? Or order one black from Aus. to try out?
I use the Staz On Ink on metal and it transfers as a dense colour, I use the black, sepia and an opaque white.
Please tell us your solution.