dyscode: It's been a while, since I bought stuff there but it never let me down.
So I gues you are logged you your Gala account, doing this. Other than that I don't see any complication.
At one point you need to give you billing address but I can think of nothing else, ATM.
Ah and the store is incrdibly slow during sales, because they put a counter on everything on a stuffed page.
Psyringe: Yep, I'm logged in, and I gave them my billing address.
No idea why it isn't working.
Edit: I wrote to their support, and they fixed it. Apparently they were trying to add Google Wallet as a payment method and it had temporarily screwed up the checkout form.
Sneaking in new untested payment options right between Black Friday and Cyber Monday might not be the best of ideas, but credit where credit is due - they responded within 15 minutes and fixed the issue immediately.