you can get them certified when you buy them here is abit of info on that.
To get them certified you need to Contact the Labelling Body at:
Level 2, 14 - 16 College Hill, Ponsonby, Auckland
PO Box 2627, Auckland, New Zealand
Ph. +64 09 361 3882
Fax. +64 09 360 3448
They will supply you with a submission form for the DVD's you wish to have certified, you can also download the submission form and the extra trailers form here. You must list exactly what they ask and as long as it is the exact same movie with trailers, galleries etc as a NZ certified movie with the same rating you are sweet.
Say you import 25 DVD's or games of the same title, the cost is $17+GST to have that title cross referenced and certified. It is then 7c for every extra classification sticker for each DVD of the same title that you wish to certify. If it has extras that are not certified, then it is $27+GST. You must also supply them an import invoice detailing the amount of DVD's that you have actually purchased to be rated to make sure you are not using them for anything else.
If the movie has not been rated here you run into big bikkies to have it done, around a thousand bucks, so probably best to make sure it is certified here