Last time Australia was involved in a search this far out (Tony Bullimore), a private Global Express? was flown from Melbourne to Perth and then used to search for the yacht. No charge was requested for the use of the aircraft. Admittedly they had exact coordinates due to a PLB being activated, however if I'm not mistaken there weren't that many SAR aircraft capable of those distances out of Australia. I believe the P3 has a range of some 5,500m which makes searching somewhat difficult with a circa 2000km search range excliding transit.
What a way to end it all... a one-way no return trip to Antartica but without enough fuel.