I think some have looked into it previously but if any "Disney" stuff then many tshirt places steer clear of it. VistaPrint is one of the only ones I have found to print these type of things. I'll take pics of how my shirts turned out when they arrive - uploaded the image that was my favorite as the graphic on the back (large) and the front has a Mickey Head with my name and Disney underneath that in the cruise logo font. The kids shirt I just did front only with the large graphic and their name on a Mickey Head. The only negative is that each person who uploads an image has to pay $5 per image to get it into their account (or less if on sale) but can make any amount of tshirts. I tried letting people order from my account last time and it was a mess because each phone rep had a different story. Yes they could, no they couldn't, they need my password, etc.
Heck, I even tried the customized Tervis tumbler with the same image VistaPrint is doing on tshirts and have had it rejected twice now - I even took off the Cowboy Mickey and the word "Disney" is not on there at all. I guess those three overlapping circles look like a "Mickey Head" or something that have flags on them
ETA: Look at the bottom of this
post as to how we tried to do it last time