From the customs page

Low value consignments up to AU$1,000 are imported free of Customs duty and taxes. Consignments of alcohol and tobacco products are excluded from this and will be charged Customs duty and taxes.

Consignments valued over AUD 1000 will be assessed for Customs duty and taxes. Duty rates vary from 0% to 10%, however most goods attract a 5% rate of import duty and 10% Goods and Services Tax (GST).

The import duty would be paid on Customs Value (actual price paid for the goods)

GST of 10% is calculated as follows:-
Actual pricepaid for the goods
Plus duty
Plus the cost of freight and insurance

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[I]and then we discovered it wasn't the Robot King after all, it was the real one. Fortunately I was able to reattach the head.[/I]