<blockquote rel="merc2013">Agree?
</blockquote>
I think this is a rather difficult question to answer based on personal experience...
Kasi for most of us here, we have only experienced living in a few cities in Australia... Most of us rather came from the Philippines or elsewhere wherein the cost of living will be relatively higher than Perth or wherever we are currently based in Australia right now.
Having said that, we could only say that Perth (or Melbourne, or Sydney or Brisbane) is an expensive city to live in...
You can however look at averages and with this, you can trust Number probably.