buying duty free on arrival ADL

[SQADL333]

I would like to know about how to go about buying Duty Free on Arrival when coming back into Australia and have never done it before.
Looking to buy a bottle of perfume for My Mother and rather than buying it in Singapore during my transit stop there of 6 hours I am thinking save myself the trouble by getting it at Adelaide when I arrive.
Any help would be most welcome

[Olympic 471]

If You choose to buy duty free in Adelaide, there is a store just before you enter inbound immigration. The also have stores after outbound immigration and in the general area of the airport too. I know that you can pre-purchase alcohol, so you pay for it when you leave and collect it just before immigration on the way into Australia. They may have this available for perfume but I am not sure.

Hope this helps