Don;t buy Duty free it a rip off.
(I can price one up for you next week if you like.)
what I suggest is shop around and buy one in AU eg Kogan or JB HiFI then use TRS.
For those unaware of TRS:
you buy product in AU,
if item (or combined items on one receipt) is greater than 300AU and less than 1000 (this can be combined for multiple travelers so up to 2000$)
and you are taking the item with you
you go to the counter after passport control
shop invoice, item and give Credit card, they then refund the GST.
so you get best price less GST
more info here
http://www.customs.gov.au/site/page4646.asp
DUty free in AU is rip off, and very small in Fiji
short of going to HK this is the cheapest way to get one