The designs are still customizable by anyone who wants to buy one - you can change fabric colors, resize the image, add text and so on. Basic white t-shirts start at US$14.95 plus shipping. There are currently two base designs, one with a blue logo and the other with red.
Note that the red shirt has a reduced sized logo - some people have noted they prefer the way this turns out. You can alter the size yourself if you want to play with this.