There are heaps of waterjet cutters in Waikato, I supply most of them abrasive for their waterjets haha
General Engineering & Manufacuturing (GEMCO) (07) 847-6979 gemcoltd@xtra.co.nz
NDL Engineering 0800 NDL Eng jan@ndlengineering.co.nz
Edwards Engineering 07 871 6560 brian@edwardsengineering.co.nz
Procut NZ 027 233 4111 mpruden@xtra.co.nz
Cullen Engineering 07 884 8232 enquiries@cullen.co.nz
Theres also Longveld, they have a couple of massive machines but mostly do their own work, can try them if you get stuck. Even more if you need in Auckland but you should get something from one of those. Or One Stop Cutting as mentioned are good guys!