Yeah just a quick and dirty one incase in desperate need of 40SC. That seems to be the walkup price. Though I just did another quick calculation.
SYD-CNS-SYD should net 30SC in discount economy. (Using JQ as an example here)
20 round trips would be enough to get SG again assuming that no are flights are taken during the period. Cheapest flight is $139 + $35 for Max Bundle. $335 return so a total of $6700 to retain SG.
What date are you looking at for that Max bundle? $35 for the Max bundle is cheap for 30SCs one way (For Aussie based runs anyway).