This is from the AU customs website:
If you arrange for goods to be brought into Australia, you are regarded by Customs as the importer of those goods. This includes purchases made over the Internet, regardless of whether or not you intend to sell or distribute those goods, own a business and if the goods are for your personal use or a gift for someone else.
Certain goods brought into Australia require an import permit. Customs might seize or detain such goods pending presentation of the permit. Alternatively, the goods might be a prohibited import and not allowed into the country under any circumstance.
All goods (except for tobacco products and alcoholic beverages) may be imported duty and tax free if their value is $1,000 or less.
Note: However, where there are multiple packages to the same addressee in Australia from a single consignor overseas that arrive at about the same time, then the value of all packages will be combined for duty and tax assessment purposes.