For a short stay:
Backpackers accommodations (Australian
youth hostels) are the best option. Prices are between $AU22 AND AU$90 / day,
depending on whether you choose the dormitory option, or a single or double
room.
For a longer stay you can rent a flat. Prices are between $AU200 and AUD$320 / a week for a studio, and between $AU240 and AU$500 / a week for one a 3 room flat.
If you want economical accommodation and if you want to meet people,
flatsharing is the best way to live in Sydney. You will have to pay your rent
weekly and it can cost from 80 AU$ to 180 AU$. The city is very cosmopolitan
so you will have the opportunity to find international roommates and have a great
time.
Guys when I was moving to AUS I used
http://au.easyroommate.com/ and it really made my search easier.
Of course there are few things they could improve - like better matching process. But anyway I can recommend Easyroommate as the best share accommodation website in Australia.
I don't know how it is in other countries but when I move back to Poland I will use it and let you know.
Thanks guys
Rep