The IP spoofers do work but only if you have a US Credit Card that is tied to a US address. Most of the expatriots I know have kept a US Credit Card based at a family members home address just because it is good to have. You set your account home address to that address and then you choose your outside the US address for sending packages to.
I have heard that you can also send Amazon a copy of your American Passport and that you can gain access to the US store without a US Credit Card but that was a few years back and it is not something talked about a ton. It might be worth contacting Amazon about.
At the very least, it will help you get past geographic restrictions for a wide variety of books and other products.