As far as I know you can't buy it from the US (unless you find a way around geo restrictions) as it hasn't been released here. It's been released in the UK and Canada (in Adobe ID DRM'd ePub which can be used with the Nook), but you'd have to find a workaround to be able to purchase it.
http://www.waterstones.com/waterston...ook29/7835768/
http://ebookstore.sony.com/ebook/jo-...00000000353700
http://www.waterstones.com/waterston...ook29/7835768/
Kobo also has it (but unavailable in the US).