I've just been in Aus, and the local paper had a story about the high cost of spare car parts in Aus, which is something I've wondered about before here in NZ.
They state that a $21,000 hatchback built from branded parts would cost $114,000.
The automakers are using warranties, secret computer codes, and authorised repair agents to force consumers to pay through the nose. ie, venture outside the manufacture ecosystem and say goodbye to your warranty.
Some of the same tricks would apply in NZ -- the difference is that the aussie regulator is investigating , I wonder if ours keep an eye on such things going on over the tasman.