I'm presuming you're asking how much HECS is...it depends on the units you take.
"In 2004, the full-time full year contributions for each band are:
Band 1 $3 768 Arts, Humanities, Social Studies/Behavioural Sciences, Education, Visual/Performing Arts, Nursing, Justice and Legal Studies
Band 2 $5 367 Mathematics, Computing, other Health Sciences, Agriculture/Renewable Resources, Built Environment/Architecture, Sciences, Engineering/Processing, Administration, Business and Economics
Band 3 $6 283 Law, Medicine, Medical Science, Dentistry, Dental Services and Veterinary Science"
However, you need to take into account that you will most probably suffer the 25% increase.
You also need to budget for textbooks, and various other course requirements (eg for biology I had to purchase a sexy labcoat and disecting kit)
Plus, theres various other costs: transport, food, accomodation (if you are leaving home), parking fees, general service fees, etc.
http://www.hecs.gov.au/