Not an awful lot...was not and remains not a popular car here in general (Aussies like BIG cars with at least 6 cylinders, preferably 8!). Parts are bordering impossible to get locally, Holden (the division of General Motors that originally imported and sold the Calibras) are not interested in supporting either parts or service and, few if any mechanics will work on them. Jap imports (Supras. Soarers, Skylines, Silvias, FTO's, etc) are more popular and better supported.
Rumour is there were only a total of around 60 Calibra Turbos ever imported and sold in Australia and New Zealand making them pretty rare as cars go, so many of the younger guys have probably never seen or heard of them. Shame really as a well sorted Calibra Turbo is not a bad ride at all...
Its tough living in the Colonies...particularly Perth, W.A., worlds most isolated city

, maybe a bit easier on the east coast though.