This has probably been pointed out before, but it's the first time I've seen it, and might be for others too. I went to pay an invoice for BuyVM today and decided to try Amazon payments. When I did, I got this:
It made me giggle in a non-evil (and very manly ) way
Availability is the key. Our policies require that payments be made from a source in the client's name (ie, not using someone else's PayPal or such) - so we're looking at adding other legitimate payment methods to circumvent the "X isn't available in my country" issue.