I agree with the comments above - with a sizable deposit you will have many 1st and 2nd tier lenders keen to throw money at you.
Before you jump into that check out:
http://www.propertytalk.co.nz/modules.php?name=cannex
Here you can get all the lastest information on the best performing lenders including CANNEX (independent financial services research org) ratings on the best deals. Often we fall into the trap of just looking at interest rates when selecting a mortgage - and lenders are on to that so they throw in 'hidden costs'. With this link you can find out who is doing what and get the best deal for you. It's all free too.
Cheers,
Donna