Welcome to basenotes!
I dont know if stores like DJs or Myer will be able to order in a scent that they do not already have on their books.
Your best bet is checking some reputable online resources such as strawberrynet.com that ship to Australia. Theres also a very comprehensive list of online retailers in the City Shopping Guides forum, and many of them offer scents at greatly discounted prices.
Im sure other members will also be able to advise you of other places you may be able to try.
Here's a few links just to get you started: