Hi,
The checkiout isn't working, the 'pay for your order now' button remains greyed out even after I've selected a payment method.

Are you sure you're not trying to purchase a DLC (or extras such as soundtracks) for a game you don't have? That would certainly keep the button grayed out.

I have a similar issue, it seems to be a localization problem as I'm a in Canada but the store currently default to USD and won't let me switch to CAD even if it is what is indicated in my profile.

Edit: The localization issue is fixed, but the pay button is grayed out if I try to use my credit card, I do not use paypall or other.

It works now, I logged off and cleared cookies. It did not seem to work but that was because I had to enter my cc security code. This might have been the issue before too, not sure. (except for earlier this morning when it thought I was in the U.S.)

Are you using Internet Explorer by any chance?

I also can't pay. My bank says that they aren't even seeing the attempt, though the GOG error screen says that the problem is with them.