Phenomenal, I've long wanted to have or make a very simple site that made tshirt designs on the fly. Defining it with prompts makes it great.

To take off more, I suggest an ultra cheap option alongside, like HALF the price or less (for people ok with absolute bottom of the barrel shirt and print quality but wanting lots of custom prompted shirts).

And maybe an ultra premium option that is like TWICE the price but the best quality shirt and printing money can buy for the value.

Also, how can we trust the site with payment info? Make sure you specify how we know it is ok. It's on its own domain, without info about who runs it, or the payment processor used, etc, all the help/about pages are 404?