Although many companies today are more open to the idea of sponsoring someone for a working visa (457) it is not always easy on top of that you will be restricted to working solely for the company that is sponsoring additionally there is a minimum salary level that your employer has to promise to pay you.
The employer also must be authorised to nominate people for sponsorship which is another paperwork barrier.
My experience is that most GA operators and schools rather not sponsor you even though it would be a great idea as it shows commitment from your side since you can't easily jump ship as soon as you have a few hours, they are almost guaranteed 2 years of service from you and up to 4 years if they refuse to sponsor you for permanent residency.
See here:
http://www.migration.gov.au/skilled/...nomination.htm
The other thing to watch out for is that if you decide to go down the self sponsored visa (independent class 136) route based on you aviation qualifications you can forget about it pilots and instructors are exempt from taking this route see the below PDF:
http://www.migration.gov.au/allforms/pdf/1121i.pdf
Immigration in Oz is a tough one i have been here for over 4 years and still do not have
PR even though i am well qualified outside of aviation.
now the other way is find yourself a fine young Oz lady.
Good luck!