Hey,
yes, the living cost depend on the lifestyle. But I guess that an average single person would spend around 2.000 AUD per month wich would also include holidays, going out, a car etc. You could survive with much less, if you share an appartment, don't have a car and don't spend much money on alcohol and party. And if furniture is expensive, you could look for a furnished flat or room. Or you have a look on gumtree and buy furniture second hand. You don't need much money to get what you need and have a good time
Cheers