The price includes the design cost too.
The cool thin gis that you can still make your own t-shirt!! Given that I am wearing my t-shirt [ actually right now ] I can tell you that the quality is really really good and it wil last literally forever [ or you break the tee ]
I also looked into this and it's really interesting. Thanks for bringing it to my attention, given that this is my little side project there's no need for overcomplication but I'm looking forward to meet you at SF!