Well one year on and they ( dive tutukaka) are still only talking about it. As they are about their ability to connect to 300 bar tanks.I was last there in October for 3 weeks, when I was leaving they told me it was due to be installed soon.... I think the Dive HQ in Whangarei does nitrox so maybe that is where they sourced it.
There are plenty of places that do Nitrox in NZ Poor Knights Divers, Poor Knights Islands, dive charters, diving, wreck diving, Tui, Waikato, dive equipment hire, Tutukaka, Northland, Whangarei are the only place in Tutukaka (gateway to the Poor Knights) that does it thought.
Trimix is another matter. You could probably count the places that stock it on one hand with out using your fingers. But search hard enough and you should find someone who can soiurce it for you.
PS RIP Kevin Bailey.