I just got a "Payment Service Unavailable" error. Despite this fact, I love your animations. Even my mother could understand those algorithms now :). Keep working hard this seems to be a good seed with lot of promises.
We found the bug. Just signup and then click on buy as a workaround.
<We were supposed to route you to login/signup page when you clicked on payment without being logged in and I promise it was working couple of days ago but we broke it yesterday -- just to make sure that we're following the golden tradition of breaking site on the launch day :)>