Tula,
Syd - Bris around $250-300 with Jetstar, tiger. Yes from perth will cost you more (but you will get the idea)
Hotel for 3-4 days $800-1000
Rental Car 3-4 days $400-500 (Usually I asked REA to drive me around for free, but not always the case)
Breakie, coffee, lunch and dinner 3-4 days...