Yes it is much cheaper to buy in certain countries.
Although, sometimes you lose way too much in getting to that location to actually benefit too much.
Flyertalk in the OneWorld section (
oneworld - FlyerTalk Forums) is probably a better place to read up on this concept.
I know a few reg's here do Done3/4's from Asia (amongst other countries) - they'll be along shortly to add their bits and pieces.
Oh, and the quickest, cheapest one to us is New Zealand. They get a saving over the Australian price.
One thing to note is that you have to purchase and ticket the ticket in that country - ie you can't go to Flight Centre and get them to arrange it (unless they have contacts overseas who will do it for you). This could get a little tricky and uncomfy for someone if you aren't fully sure of what you are doing. (ie wiring money to Colombo (Sri Lanka) or faxing/emailing stuff back and forth - or frantically picking up a ticket at the airport during a turnaround!