I must admit that I really don't trust some of the statistics and median house prices quoted.
The median prices and suburb guides/prices are shown in the paper here every few months.
Some stats are totally wrong as there are far too few houses sold in certain suburbs.
Our suburb of Onkaparinga Hills has few sales and the median price varies wildly.
I look for the busier suburbs such as Morphett Vale to give me an idea.
I just had a quick check
Doesn't go by average prices, (once you register) it goes by actual price at the last sale.
Which means, as you have probably already guessed, you can check what price houses are going for in a particular area.
Where I live there are no houses that have less than four bedrooms, so working out an average price is much easier than were there are a mix of residential types.