I didn't think of that. I can put my US address but I still would need to pay with my EU card. I thought they determined region simply by your IP address. I logged out of my account and the prices switched to dollars, then logged back in and they were back to euros. The thing is, there's no way to change your account billing address on the site. Apparently once they have you linked to the EU, they keep you there.
I could try to make a new account, set the region to US, and see what happens if I try to pay with my EU card - but somehow I think if I have the same credit card linked to 2 different accounts, they'll detect it and ban me or something. They seem to have a lot of measures in place to make sure anyone outside the US has to pay more, including the new no-gifting/trading flag on certain games, and the instant deletion of any thread on the forums that refers to the price difference between regions.
If I have my sister make an account with her credit card then gift the games to me, and I'll pay her back in cash, that might work... Except I also suspect that if someone creates an account only to gift games, they probably watch that too.
The strange thing is, on some parts of the site I see the dollar price, and on others I see the euro price. Like the site isn't sure what to do with my US IP address but EU billing info?