Anyone who knows how to tie-dye a spiral could do it (and most tie-dyers have done many spirals). They will just have to add more water to their dye, or less dye powder to their water, to get the pale colors.
I'm afraid that I personally cannot take on any new projects, but you should be able to find someone who will dye your shirt for you. There's a listing of dyers willing to take on custom projects on my site, on a page entitled
Where can I find someone to dye my clothing for me?. You can also look for a tie-dyer on Etsy who does work that you like, and contact them to ask if they'll do a custom tie-dyeing job on your shirt.
You could pretty easily do this yourself. You'd want to get some plain white cotton t-shirts, for testing, and a good tie-dyeing kit, such as the Jacquard tie-dyeing kit or a kit sold by Dharma Trading Company or PRO Chemical & Dye. (Avoid the Rit tie-dyeing kit, which contains the wrong type of dyes for multicolored tie-dyeing.) I already linked to a page with instructions on how to do it. You would want to dilute your dyes with perhaps five times more water than the usual instructions direct (which means the kit will dye far more pieces.). If you keep your dyes in a cool place, and don't let them get contaminated with soda ash before use, you can store them for a week or more, so that you can look at the results of your first attempts before you work on your favorite printed shirt.
-Paula
