It's the American Atheist store - they have all kinds of stuff - I bought an atheist coffee mug! ;D
or, you can make your own [buy t-shirt decals - you can get printable decals at staples - and try one…"
"I've gone into cafepress.com a few times looking for stuff. You can search by theme. Or type atheist clothes into google and see what turns up. I got a fun one through questionablecontent.net and Jeph Jacques' collection of merchandise.…"