Oh, forgot to mention: buying a campervan is pretty easy. many backpackers use old vans and sell them on when their time in NZ is up. Our own van, a very cosy Toyota Lucida 4WD was bought off a desperate German lad who was on the plane the next day. Needless to say we drove a hard bargain, but repaid him in other ways by introducing him to a law firm in Brussels where he now has a job...

When I get home I'll put up the URL of a backpackers site on which many vans are advertised. You should be able to find someone who's leaving soon and the prices asked tend to be directly proportional to the length of time the vendor has remaining in NZ. Bargain like crazy and you will probably be rewarded.

The other possibly is www.trademe.co.nz, the NZ auction site which has thousands of cars and vans for sale. Prices here are general values and while the possibility of finding a steal exists, it isn't quite as likely, since you are in competition with everyone else in NZ who's looking for a ride.

The thing to look out for in NZ - apart from the general cautions which go with buying an elderly vehicle anywhere - is that the WoF (Warrant of Fitness) is current, and hopefully that it covers the time of your stay. This also applies to the registration, but if you have a WoF on the vehicle, getting or renewing a rego is easy and (by UK standards) fairly cheap. Make sure that the vendor is prepared to go through the transfer of ownership, or you will have bureacratic problems.

Unless you are a very competent mechanic, avoid like the plague any vehicle described as "rego on hold" (= no WoF, probably no hope of getting one); "as-is-where-is" (= a junker).

Good luck!