Never had this problem before, read others have elsewhere but no idea why. Try Offgamers instead, prices are broadly the same.
I have same many games to play at the moment, I'm in no rush to buy it.
You have set up a new US account, right?
even when I go through an incognito link, when added to cart, it then asks me to log in to my account and then tells me 'Your account information doesn't match the locale in the URL.' so puts me back to the uk site
Log out of UK store, clear cookies etc. and try again, or just open up an incognito tab in Chrome, either should work