An AOC can not be 'transfered' - It is linked to the company, individual and/or ABN number.
In order to buy an existing AOC you must therefore buy the company (and therefore assume any skeletons that come with it) - not advisable.
Contact the CASA service centre (CASA web site). It may take up to three months for the service centre to process but they can give you a better timeline.
And that's just the service centre. After that you will have to go through your local area office who will put a borescope up you.
I was just quoted 9 weeks to add a new type to my AOC - just think, 2 months of lease payments before you can operate!.
Whatever you do, start small. Apply for the most basic AOC just to get the runs on the board. If you want a flight school, just start with the basic PPL, NVFR. If you want a charter AOC, just ask initially for SE VFR.
Apparently, the whole process of applying goes on-line from September.
If you try and get a complex AOC off the ground from the word go then you will have a tough time.
Good Luck