Yes - more than 15 years since I worked in Perth but have recently heard many reports that costs there have risen greatly. However, suspect Sydney still the most expensive (apart perhaps from Darwin and some remote areas) with Melbourne, as I understand it, generally on a par with Sydney.
Big difference also in sq m estimates for apartment blocks or small lot two-storey townhouses as opposed to regular suburban single storey houses. Ironically the larger the houses the lower the typical cost per sq m. Some of the estimates in this thread apply to regular housing.
In our experience the level of finish and fit-out is also a big variable - that last 10% to 15% of a project seems to gobble up the cash and typically requires a huge effort.