I'm just about to order the bulk of this years leds and I thought I'd better check beforehand what the dollar threshold is for imports coming into Australia before there is import duty.
$1000 (including shipping) is the threshhold. Over this point, you are liable to GST, plus import tariffs (which vary depending on the type of product), plus a clearence fee of sorts from memory.
Imported items are classified by according to their intended use and construction (Tariff Codes) and import duty is will be charged unless there is a Tariff concession. Generally the Tariff concession rate is 0% for LED lights and controllers so duty is not payable. If you import these together with other goods you may get these classified in another way.