Ink Monkey is a great company that can screen print designs on almost anything. They charge by the section, but you can get a great deal if you want to design something for a group. They do sell printable clothing there as well as many other different things you can print on. It's great because they work with you to make sure your design looks good on whatever you decide to print on, especially if they have technical problems that doesn't allow certain aspects of your design on it. They're reasonably priced I guess as well as prompt.