There are some fantastic B class fares that AA has from South America to Australia. $2000+ ex-SCL return, $2500+ ex-EZE and Brazilian ports.
In May I did POA-GRU-EZE-ORD-HNL-SYD-HNL-LAX-ORD-EZE-GRU-POA.
EZE-ORD-HNL,HNL-LAX-ORD-EZE cost a total of 20000 miles to upgrade.
You can even route these fares via NRT/HKG to get to Australia.