We are in Adelaide on a 489 visa and have just bought a property after renting for nearly a year. You will need to get FIRB approval which costs $5000, but is just a formality. The approval allows you to purchase a single property for you live in. You can't rent out the property or any part of it and you can only have one approval license i.e. you can only buy one property while on the 489 visa. The only exception is if you buy a new build property and then you don't need the approval.
The other thing we found is that some banks won't touch the 489 visa e.g. Commonwealth Bank. Some others will want a large deposit, but if you shop around there are a few organisations that will lend up to 80%. Of course as a 'foreign investor' you will not be entitled to any of the first time buyer incentives.
I hope that helps.