I am really glad someone else had this problem, but it only seemed to happen at my home IP address. It works on my laptop everywhere else. Try a different browser, otherwise go to a friends house and order your stuff
I actually emailed them, their webstore doesn't work for many campus internet users, it's physically impossible to get to it on any browser on the MSU wifi so I have to use my phone. If you're at school that could be the problem.