Unless you're going to Hong Kong, in which case it's easy (you don't even need to leave the airport). You could try calling Apple HK at 800-908-988 (sales support number on the website) to ask.

Selling unlocked phones in HK is pretty much intending them for a worldwide market. Lots of people travel through there.

I'm sure apple are aware that buying unlocked iPhones direct is something that people are interested in but I'm guessing that carrier contracts prohibit that in many countries... hence the countries where this actually happens are few and far between (Italy and HK are the only two off the top of my head, though Australia might be one too)