Firstly, a big thanks to the folks at Australia Frequent Flyer, particularly wjohn, whose post let me find this.
It's a bit difficult to explain, so bear with me (it's worth it!)
1 - Into Asia
2 - Asia to Europe
3 - Europe to America
4 - America to Australia
I've been looking at late November (post uni exams), and early December. However, with a few quick search there seems to be availability in October, March, and April. There's so many different options, so search and try your luck!
Leg 1 - Into Asia ($309)
Book a one-way flight on a budget carrier (e.g. JetStar).
Leg 2 and Leg 4 - Asia to Europe + America to Australia ($734)
There is an amazing deal for leg 2 and 4 on Etihad.
Searching for a multi-city flight on www.skyscanner.com.au:
1) Bangkok (BKK) - London (LHR)
2) New York (JFK) - Melbourne (MEL)
NOTE - These cities may be altered to suit you better!
Instead of Bangkok, another option is Tokyo (similar price). Instead of London, you can pick any European city that Etihad flies to (they are all similarly priced). Instead of New York you can try Los Angeles (similar price). Instead of Melbourne you can pick your Australian city of choice.
Leg 3 - Europe to America ($555)
Find the cheapest flight you can from your European city of choice to your American city of choice.
With my example:
Melbourne - Bangkok - London - New York - Melbourne
MEL - BKK - LHR - JFK - MEL
Total = $1597
P.S. You could potentially throw in a stop-over in Abu Dhabi if you alter the multi-city search :)
Bangkok - London + New York - Melbourne (14th October - 28th October): https://imgur.com/zq8fx3o
Tokyo - London + New York - Melbourne (19th November - 8th December): http://imgur.com/3ESHPdE
Bangkok - Amsterdam + New York - Melbourne (9th March - 22nd March):