Being under $1000 hasn't applied for a while now, courtesy of Harvey Norman who pressured the government to drop it and charge GST on anything from overseas. Whether you will actually be charged GST is hit or miss. The company selling you the goods is, according to the government, supposed to collect the GST and forward it to them.

As far as I know the only people doing this collecting overseas are ebay/paypal, Amazon and Aliexpress.
Sometimes the shipping company will do it but I know people who have ordered from the US and not been charged GST.