I am surprised that you are allowed to keep species that are native to Australia. Here in the USA, we are not allowed to have any species that are either natives or migrate thru, and I believe it is the same in Europe. I notice that many Australian sites feature Lady Gouldians, Owls, Stars--all natives. Is this done to encourage breeding, so that these species will always be available? Is $25 for an Owl finch in US dollars?
I have visited a number of Australian aviary sites, and many have very large aviaries--I guess your climate is conducive to keeping the birds outside all year.