Here's the short answer:
Download this 2004 schedule of artists hourly rates, read the whole thing carefully, and then multiply all values by 1.353 to get hourly rates for early 2012.
The 35.3 percent increase is the increase for Australia 2004-Dec 2011, calculated from the Australian Bureau of Statistics (ABS) website.
Hope that helps!
Remember, using experienced artists will in the long term save you time and effort, and give you a much high quality result.