Gerby
In the Qantas case they haven't actually done any preserving. The Longreach aircraft are owned by the QFM while the Connie is owned by HARS. THe DC3, Hawdon was preserved by TAA,now part of Qantas. However Qantas has helped in all these efforts by providing transport and engineering support.They also donated the B747 200 but probably got a good tax deduction from the donation.
The current HARS DC4 and Convair 340 projects don't seem to be sponsored by any airlines and I don't think that the recent Catalina arrival was either.
I suppose the results in Australia are a team efforts of individuals setting up organisations which are in turn supported by business, Government and the public.Probably a good way to go as everyone has an interest, so the projects should have a good life span.
Wunwing