One Stop, my first piece of advice is buy local.
You have some really great alloy manufacturers in the South Island offering really good value so start with them. Add Lazer, Southern Boars and Stabi to your list.
Look at all the options.
You do not mention how many folk will be on board - family of 6 or just a couple?
Besides cruising, trout fishing, sea fishing, skiing or wake boarding.....
What kicks your family into gear? Can you do it with 60hp or do you need 150hp.
Pick a base line boat to start the search then buy better. Like this brand new Frewza F18 with 100hp four stroke for less than $40k.... http://www.trademe.co.nz/motors/boats-marine/motorboats/auction-1235504432.htm
Now you can bargain with value like that.