No difference anywhere within Australia - the price is the same.
Big difference (both in terms of cheapest locations and absolute price) for LONE and DONEs.
Australia is not too bad for a LONE4 and when positioning taken into account probably the cheapest for you.
I believe South Africa still leads the DONE4 race. Pakistan and Sri Lanka cheapest in Asia and NZ still cheaper than Australia.
Use this spreadsheet for most current prices:
http://sites.google.com/site/rtwfares/home