You may be right that they just don't want to deal with (or have not yet negotiated) foreign shipping agreements.
What number did you end up calling?
So far, I've submitted to their online form and had two back-and-forths. The first just said they couldn't sell a nook outside the US. I responded by clearly stating that I understood about publishing territory and didn't want to purchase books, I just wanted the device to read my local libray books and free downloads from Gutenberg etc.. They replied that they actually can sell certain book to people in Canada, and nook users in Canada can buy them, but they still can't sell a nook outside the US.
So my next question will be how do I become a nook user in Canada... which I expect they will reply with "buy one in US and bring it home".
