"Due to copyright restrictions, the Kindle title you're trying to purchase is not available in your country: United States."
I recall reading there's a way to trick the system, I think by changing my account address to somewhere in Japan. I may lose access to my US-purchased content (while virtually living abroad), but can always "move back" later. But then I'd lose this. But apparently there's also a way to download my Kindle content, and strip the DLA, and OMG WHY'S IT GOTTA BE SO DIFFICULT.