I can't check until tonight when I get home from work but are account regions locked? I know mine currently shows the US but when I travel to Japan next month, will it update?
Disclaimer: AC mentioned it's against the TOS, but I've done it in the past - Military deployed to the middle east, various countries. I've had issues where I 'had' to use my VPN* in order to purchase games on steam due to mismatches between my local IP and my CC(payment method). Even picked up some cheaper games in a couple spots.
I didn't receive any bans, but given that I was actually *in* the foreign country, but VPN's back to the USA in order to use my US credit card to buy a game for my US steam account, I figure I'm not the target audience. Probably hard to tell I'm VPNing as well given that I used a VPS that I'm the only one VPNing from. The pingponging might be a clue, but I wasn't using it to buy lots of 'gifts'(IE act as a retailer). Even then, they might figure out that I'm likely a US military person from the location and not want to deal with the butthurt and negative publicity when I'm not actually getting a price cut.
*From a VPS that I control, not a public VPN service