The guitarpraise shop is up! I've put up a couple of t-shirts, the prints are the same, just that the cutting and colours vary. I'm also selling at cost, at no profit, so the t-shirts are as affordable as I can get them to be (about US$15-20). My favourite is the dark brown one design:
There's also a notebook that you can use for your sermon notes, and a cute but useless tile:
I bought a pair to try out - the t-shirts are Hanes tees, and the quality and fit is pretty good. To get your size, you will need to measure your chest, and match it against the chart provided in the website. Leave me a comment if you've gotten something for yourself!