If you want your print-on-demand service, don't forget to check the banner at the end of this shop page.
Check out this general print-on-demand shop, a great place with >150 products and fabulous, easy to use software.
You can pick a design, or even upload your own. Then you put your design on the article of your choice, customize everything until you are satisfied and press order button. Discount is applied on orders over $200. Partner is Spreadshirt, a reliable print on demand supplier.