Teepublic has virtually anything you might think “I’d like that on a T-shirt.” It’s surprised me many times. Unfortunately, it also does a lot of unlicensed stuff and they really don’t have a problem selling things that the original artist doesn’t get compensated for (I got a shirt taken down because I knew the artist and I knew he had nothing to do with it).
But that’s probably the case with a lot of these companies. It’s definitely the case with Amazon. So I try not to worry about it, especially not with a shirt like that.