@Mykv craft n ride had a sale recently for free international shipping. Try connecting with those guys for a deal. Flight Fins wanted $70US to ship to Australia. CnR were $50US before the sale came up.
There will be tyre sellers in NZ, but may not be the best tyres for a OW. I work with a guy who races karts and tried a used dunlop from him. Wasn't a good experience. Very square profile, so a step backwards from the Vega even.
The Hoosier distributer in Australia didn't have the right tyre but could get it in. You could try hooking up with other NZ guys and order a bunch in.