For a start:
The Tuatara LP comp. CD Presents (!) put this out in 1986 or so, it's a USA-press overview of the early NZ scene. They go on ebay for $7 or so alla time. Or $25 if some trust fundies start tussling (or a NYC store is listing it). It has the hits and some great arty obscuros.
For the later 80s take, get the "I Wasn't Made for These Times" comp Lp, that will run you $10-15, and it has all of the second wave Flying Nun bands before the label starting sucking it around 1991 or so.
And for the random left field NZ experience, track down the Builders/Bilders/Bill Direen stuff, mostly on CD as the vinyl is very $$, prob on Soulseek I'm sure. His stuff is sort of the bridge between the Clean and Dead C, or say the popsmithery and the fuzzed-out drug 'veins'. He's all over the map style-wise.
You can pick up any Tall Dwarfs stuff pre-1988 and get the picture. Chris Knox solo starts to stray into Robyn Hitchcock preciousness in the 90s, but the 'Seizure' lp is still mighty gear.