I wouldn't buy from Oz if you are coming here for a holiday: enjoy the holiday instead!
Even with the 10% GST off, Oz prices are still well over what you would get from US or UK or Europe. And, your ranges are so much bigger!
I adore Cultstatus, and buy from there whenever it is new-season stuff that I really don't want to wait for, and because Lily provides such excellent service.
The girls at Parlour X are also very nice. But then again, as bagilicious says, Oz import tax on luxury items makes Bal bags from Oz quite prohibitive for even we locals, so that we buy many brand-new and pre-loved bags from overseas.
If you really want to buy a Bal bag, I'd suggest following karenwk's advice of emailing Aloharag, and also ******.
Good luck with finding your dream bag, and have a great time in Oz. Truly, everything about it is wonderful - except for brand-new Bbag prices