bitcoincambodia.com is cheaper when you compare it with Western Union. And Western Union is only in big cities available, but WING is everywhere. And to pickup money with WU you need a ID-card. But many people in Cambodia have no ID card.

There is a fixed-rate exchage service for Bitcoin in Cambodia.
Here is the URL: http://bitcoincambodia.com/

It is possible to exchange BTC for USD, or back. People why live in Cambodia not need a bank account or something like that. The money will be transferred via WING, which is available in almost each city. The receiver in Cambodia need only a phone number.