Just tried ordering a Nexus7 (since N4 orders are not open yet) while connected on a US-based VPN and unfortunately it seems like Google Wallet won't accept non-US credit cards for the hardware purchases. (My usual non-US cards are listed there, which it won't let me select)
That means if you are planning to purchase the N4 from the US with your international credit card (planning to send it to a hotel to a mate or yourself to bring it back home) you'll have to find another merchant as the Play Store won't do. I also checked purchasing with the gift cards, they too are not redeemable for hardware purchases.
So let's hope that Amazon sells it with a reasonable margin.
Nexus 4 (rev_10, Fast) running CM10.1 nightlies with Franco Kernel