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 :)>
<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 :)>