Colin, Oratia nursery should be able to offer some advice if not provide them.
Failing that, Fern Factor, Christchurch would be worth contacting. However I am unsure of the wisdom of taking S. Is. genetic stock to the N. Is let alone as far north as Auckland. But Paul may know of a specialist propagator in the upper north
http://www.fernfactor.co.nz/about.html