
Anyway, if you're going over to meet her, do you supposed you may crash at her place, knowing how gaga you go over her? That can save a lot.
And if you want to spend cheaply, better go during end of the year. That way, you don't have to spend on winter clothes

Tripadvisor is a good place to start for your budget homework. Another way to do it is to go to the national library, borrow Lonely Planet's 'Australia on Shoestring' and READ! Very handy in your situation.
(And if you're meeting her for the first time, better prepare a nice gift.)
I don't think AUD1.5K will be enough without the above (free lodging, summer wear, takeaway).