I went this time last year and loved it! i went for 2 months and had about �2500. We stayed with family friends over there for some of the trip though which saved abit on accommodation!
Where abouts are you going?
We started in Adelaide and worked our way up the East coast, Sydney, Byron Bay, Surfers paradise, Airlie beach etc.!
For just 9 days i reccommend planning things you want to do in advance...its far too easy to just arrive and spend the time just sunbathing or something! Some trips only occur on certain days and you dont want to miss out on anything! You will want to stay for so much longer!
I reccommend you stay in hostels wherever possible. This will save you loads of money. www.hostelworld.com is a good site! Read the reviews before booking some are absolute dives!
Food can be quite cheap depending what sort of diet you have...you can get a three course meal with wine for about �15.00 and tourist hot spots (excluding cities) generally accommodate for most budgets!
Please let me know where it is you are going and i will try to reccommend some places to not miss out on!
Hope that helps! Any other questions, please ask! x