Grab a free property report from ANZ.
Find about the suburb data as well.
Update-
You would require a email to download the report. unless like ING one..
thanks @Domicron for pointing it out.
If you think, you will be spammed, you can use some fake mobile number. Still the report works.
They aren't ever accurate. They use an algorithm of previous sales in the area, adjusting for number of rooms in the house, and maybe land size.
Land size is often completely wrong especially for units. Age and condition of property isn't considered by the algorithm.
So it's using bad data to guess a price for your home.