Originally Posted by
christep
There are cases where this isn't true. People have chosen to take a slightly higher price for the convenience of purchasing in a different country from the origin, or of ticketing in a cheaper country for departure from a more expensive one. For example,
here Wasabi Tofu describes buying an ex-ARN ticket in Tokyo.
SOrry, what I was trying to say was that even in this case, you will have to show up in ARN because you are starting your trip there. I have purchased an ex CPH ticket in Australia (*A) but I will still have to start my trip in Denmark next year.
Unless I am mistaken, you can not buy a cheap ticket ex JNB for example, skip the first segment to LHR and actually start your trip there.