Tried to purchase some music from Amazon in digital form (selected songs from Broadway musical shows that are not available on iTunes). First time around got blocked by a message saying they could only sell music to US customers. Thought they might be doing IP checks so arranged to have a US IP and tried again - same message. Then tried my US credit card and it went through fine! So like iTunes they are only checking if your credit card is a US one - not checking if you are actually in the US. iTunes initially does put up a message saying their (US) service is only available to US customers but then allows you to purchase if you have a US credit card.; At the current exchange rate US99c for a song is a bit better than NZ$1.79 I think is what NZ iTunes charges.
As a matter of interest the music was DRM free, MP3 256kbs so pretty good quality.
Larry