That seems pretty good value at around $4/SC.
I had a quick look playing around with some options and MEL-BNE-CHC-AKL one way is about $1,100 and earns 165 SC's at a rate of $6.67/SC. Doing that twice (ie: return the same way) would get you to 330 SC's.
Of course when you work out the "true cost" of the SC's in your routing you will need to add in the costs associated with your positioning flights (flights + any additional accommodation etc) and that will quickly bump up the $$/SC.
