Amazon has changed a lot in since the time I last used it over 10 years ago. Back then Amazon.com WAS Amazon, that was who you were buying from and getting it shipped from their warehouse.
Now after 10 years of being out of the loop as to what they do, I went back a couple of months ago to find some vintage computer games I've been collecting. Now not only is there is a Amazon company, but also hundred's of other sellers, similar to like Ebay, but all "Buy It Now" instead of auctions.
It's confusing because as you and I also found out, some sell overseas, some don't. And it's never 100% clear who does until you get to the checkout and enter your address. It's REALLY frustrating particulary after I found a game I was after in what looked to be close to mint condition for a great price on the Amazon.co.uk website. But they wouldn't ship overseas!!! Grrrrr.....
In the end I just went back to Ebay. I've been a member since '99 (100+ positive feedback), used Paypal many times, in fact I prefer it for payments since it's instant so I don't have to wait around before shipping off what I've sold (then I spend it

). Makes it all very handy. Never had a problem with either service.