I took the Rough Guide to NZ out of the library and it says under ‘cars’ be sure whatever you buy has its warrenty of fitness certificate, valid for up to six months. This needs renewing every six months so you don’t want only a couple of weeks validity left. Also, check it’s been registered recently. Registration costs $110 every six months. You can get an AA vehicle inspection for $100 or so, if you’re worried you might be buying a lemon; but for $750, it’s hardly worth it. The Rough Guide says reasonable cars start at $1500 …! Also, if you’re buying privately, they suggest calling Autocheck debt check on 0800 658 934 to make sure the seller doesn’t owe money as you the buyer will become liable to it!
Well, that’s as maybe.
Personally, I’d suggest checking the tyres to make sure they have some decent tread on them – ie, not shiny and bald – and asking the seller to show you where the jack is and demonstrate where to put it under the vehicle to jack it up (specially strengthened places). Also, find the spare tyre and give it a prod to see if it’s not flat.
Ah, the joys of car purchase!

A NZ rule Annika might not be familiar with (apart from driving on the left) is you’re expected to give way to traffic crossing or coming from your right. So, for example, if you’re pootling along and about to turn left into another road and a car coming towards you wants to turn right into the same road, he rather than you gets to go first.