Chris,
Read the other threads on becoming an SIA pilot carefully. There are many such recommendations from ppruners who're either with SIA/MAS now or have been.
Ironically, a well-recognised flying school in oz doesn't usually correspond with "affordable" and that depends on YOUR definition of affordable too.
CPL packages range from 30K with smaller schools to 45K or more for more internationally recognised institutions such as BAe Adelaide. There are really a multitude of schools out there offering training to CPL standards but you must consider if you really need it.
For starters, SQ offers a cadetship so you don't necessarily have to have flying qualifications as they will take you through the whole way. Not sure for MAS though.
You might consider asking about good schools offering CPL training in the Dunnanda & Godzone forum since you're asking about australian ones. Hope that helps.