I am just curious if anybody has ever shipped a high volume overseas and explored non-postal service options such as air freight (I am thinking US to Australia, but could be anywhere).

For high volumes, is there a point at which using a freight service or company becomes cheaper than the post?

I have been casing a few shipping companies but most of them do not give rates online. Obviously a competitive business.

Looking at Australian companies shipping the other way, air freight seems to be about 20% cheaper than post  for volumes in excess of 20kg - but with the rigmarole associated with it, may not make much of a difference.

Probably very large volumes in a shipping container would make a difference. I'll have to form an Australian RPG buyers consortium!