Okay I love the pattern and I know your dilemma. I would suggest that you buy a whole bunch of white fabric (whatever you want) and dye packs.
Just dye your gradations in each of the colors. I did this last year for a twisted triangle (from Simply Quilts show).
There was a great link on dying a few days ago and the OP of that link did a fantastic job.
Worth a try :) :)