Have a look at Minovation in Perth too. The school is run by a Brit and she's very familiar with the costs of conversion.
You'll save some money especially in the hour building stages. You can get an IR on a PPL in Oz (just as you can here) and thus you can convert that IR to a JAR one using the 15 hour abbreviated syllabus. (Do check LASORS though!!)
Probably the cheapest way if you really want to go to Oz is to get a PPL and possibly IR there and do some hour building.
There's lots of Oz to fly around (trust me, I know!!) and the weather is generally good so you can get it done in a reasonable time.
PPL conversions aren't much drama.