The thing is, what do you wanna do after that. As far as I know, you won't get a work permit on the basis of a one year post graduation study after you've done it, since they require two years of study. So yeah I think you'll be coming back to Pakistan. My personal opinion is that if a person does invest so much money then they should at least work abroad for a few years if not get permanent residence status there. That's why I opted for Canada instead. I would suggest you to visit educational consultants and ask them about the current policies of Australia for international students and foreign workers. And also plan out your future, ask what opportunities you will get after you're done with your masters. First meeting is free so try to get as much info as possible.
Hope this helps.