Row2aisle, may I know why you purchase the garmin maps from amazon and not the local garmin distributor? Is it cheaper?
If you already have a device, it makes sense to add the maps before you get to your destination. That way you turn on the device, select your map, and away you go.
Also - to buy Garmin maps via a retail store will cost you around A$190...
http://www.ja-gps.com.au/Garmin/city...-2010-microsd/
Finally - if you're going to come to Australia, and don't have a GPS, how about
:
1)
Buy a TomTom Go730 for $100 from Amazon
2)
Buy the Australia map for $80
TomTom and Garmin are both good - the TT maps are cheaper. They are the same ones as Garmin, coming from Sensis Australia (not Navteq).
My original recommendation stands - go to Officeworks and buy the cheapie.