As long as you keep the total value of what you are importing under $1000, you don't get hit with GST.
If you were to, say, buy a PC overseas that costs over $1000, prepare to get slugged when it comes in through the post. If you have someone send something over, make sure that they price it as $999 on the customs form. I sent myself a computer from overseas and in my honesty/stupidity, priced it over the magic $1000 value and ended up paying about $200 in duties.
Actually while you are in Australia, prepare to get slugged everywhere for tech. A high Australian dollar, and the fact that we don't locally produce any tech (we just dig rocks out of the ground and sell them), means that overseas tech companies here charge whatever the small Australian market will bear, and usually they typically price it on the side of unreasonable.
Do I really need to talk about how terrible the internet speeds are here? No need to mention that in some places, the best you can get is 2Mbps ADSL? No? OK.