@tranglos: Is Amazon complaining because:
1) Your IP appears from outside the USA?
2) Your account shows that you live outside the USA?
3) Your means of purchase, (ie. credit card), shows you're outside the USA, (which really shouldn't matter)?
Who knows. I guess it's not the IP, since if it were, they might just not show the listing to me at all. It's not the cc number, because they haven't asked for it yet (though they have it on file). I browse logged in, and they almost let you complete the purchase, until the page where you would enter or pick your cc. So I suppose it's (b).
When I browse audible.com (which is also Amazon) logged in, they don't show the audiobooks not available to me. But Amazon.com does, the teasers that they are.
Something to try next time.
1a) Use a free VPN, (eg. TunnelBear).
2a) Change your home/delivery address, (FakeNameGenerator). Address doesn't matter for digital download.
3a) Purchase a Gift Card and then change your home/delivery address.
I suppose one of these could work. For (1a), I would be wary of completing a secure transaction through an unknown (to me) entity's network. (2a) doesn't work; I tried that once when I wanted to buy a Kindle book that was "US only" as well.
But I have an ethical (kind of) block against workarounds like these. Perhaps using the combined brainpower of Donation Coder regulars (and ir-) we can figure out a way to make this happen. Whatever we came up with, it would have to involve lying to Amazon about who the buyer is, so in the end it might be problematic in one way or another. But more importantly, we should not have to do this in the first place!
It's like discussing personal privacy against state and corporate snooping. Techies will say, just encrypt your email, or use Tor - and yeah, it'll work (up to a point), but it will only work for the techies and those lucky enough to have friendly techies nearby. If we have to resort to these sorts of techniques, we've already lost. Everyone has.
Do tell me if my horse is high enough already :-)