If you want to find data on auction sales there are two services in Australia that you can use.
Australian Art Sales Digest
The Australian Art Sales Digest is a database of past auction results of over 300,000 works by more than 11,400 artists who have either lived or worked in Australia or New Zealand, offered for sale in Australia and New Zealand over the last thirty-five years. Our data covers over 1,500 auction sales from over 50 auction houses, and extends back to the early 1970s.
Subscriptions are AUD $A30.00 for one month and AUD $175.00 for one year.
Australian Art Auction Records
Australian Art Auction Records is a service that documents historical art auction results and makes them available via subscription.
Subscriptions are AUD $28.00 for one month and AUD $135.00 for one year.