The Customs value of goods imported into Australia is based on the value of the goods as determined by the importers commercial invoice and is typically equivalent to the Australian currency purchase price of the goods.
When the goods are valued at more than AUD$1000 threshold (or if they include alcohol or tobacco products of any value), a Customs value will be determined which is used as the basis for calculating the value of any duty and/or GST.
The Customs value is combined with other items such as customs duty, international transport and insurance costs and, where applicable, Wine Equalisation Tax to produce the value of the taxable importation (VoTI) which is what the GST calculation is based upon.