Note, though, that despite being able to pay another the price of the country of departure there are few competent oneworld airlines who can properly price and sell these tickets to begin with. American is the key one and has a dedicated round the world desk in Dallas (+1 800 843 3000). Note also that the deep discount countries of departure have dried up. South Africa, Namibia, Egypt and Mozambique are all much higher than they once were. I'm lead to believe Japan is about as good a bang for your buck as you can get and for us Aussies is probably easier and cheaper to position to.
Depending on exchange rates at the time, South Korea can be good as well.
There is an extensive thread on FlyerTalk with much advice including two or three resident experts (one from Australia). Your best bet is to post in that thread or, for some local help, post your planned itinerary here (even something like where you'd like to start from and what cities you'd like to visit) and we'll have a crack.
There are at least 2 or 3 people from Australia active in that thread. As far as I can tell, those people are also active here.
I've done a oneworld RTW of some type each year since 2006. The first year was an LGLOB29 (mileage based global explorer) in order to use JL prior to their joining the alliance. After that I did LONE4's until 2010 when I started combining a DONE3 from Seoul or Tokyo with a DAS13 (Circle Asia and South West Pacific).
When I was doing the LONE4's, I could only get mid way between sliver and gold. Since 2010, I've had no issue getting platinum. With the first DAS13/DONE3, I had just fallen back to bronze right before departing due to the timing of the trip, and got to platinum just before I got home.
It has become harder to get SCs for the last few years since the QF "simpler and fairer" changes. It will be harder again this year with the AA booking class changes and no longer having the "D books into A" on 2 class US domestic.
This is just the RTW part of my trips since I started using booking J. (The DAS13 part has been almost the same each time, with the 8 allowed flights getting just under the allowed 13,000 mile max)
2010: NRT-SIN-HKG-JFK-DFW-ORD-MCO-DFW-SEA-JFK-CDG-HEL-LHR-DXB-LHR-HKG-NRT 41637 mi
2011: ICN-NRT-DFW-ANC-DFW-ATL-ORD-SFO-JFK-FCO-MAD-LHR-DXB-LHR-SIN-HND-GMP 42573 mi
2012: ICN-HKG-JFK-MIA-SEA-ORD-LAX-IAH-ORD-AMM-MAD-LHR-DXB-LHR-SIN-NRT-ICN 45934 mi
2013: HND-HKG-JFK-SFO-ORD-RDU-ORD-MIA-BCN-HEL-LHR-DXB-LHR-PVG-KUL-SIN-HND 42702 mi
2014: HND-HKG-JFK-BOS-MIA-LAX-IAH-ORD-DOH-CDG-LHR-DXB-LHR-PEK-HKG-SIN-HND 44433 mi
2015: HND-HKG-BOS-DFW-LAX-MIA-JFK-MIA-ZRH-HEL-LHR-DXB-LHR-PVG-HKG-SIN-HND 42484 mi
2016: NRT-JFK-DFW-PDX-LAX-DCA-DTW-DFW-DOH-OSL-LHR-DXB-LHR-ICN-HKG-SIN-HND 44572 mi
Last year on a DONEx, booking a 2 class AA domestic flight would book you in A and get First class status credits/points, however if using a QF codeshare, you'd get booked into D. Thus the AA code on DFW-JFK would give you 120 SC while on a QF code, you'd get 80.
Now, with the AA booking class changes, and the QF earn cuts on AA, that same flight would get you 40SC on an AA code and 80 on a QF codeshare.