Hostels are pretty great in NZ. They are clean and rather affordable. Their deal is pretty much the same as you would get in Europe. For $20-25, dorm rooms include continental breakfast, linen (depends), shared toilets–or you can get a double room with a private bathroom for about $50-60.
If you’re after a double bed and a bit of privacy, I recommend you go to a campground and rent a cabin. You can get these in the off-season starting at $45. But you have to negotiate what the terms are as these change depending on the Campground.
If you go the Camper-van route, you will still have to pay $20 for a campsite to use a toilet/shower.
Motels/Hotels will be at least $100/night, usually more.
Remember that the NZ dollar is even cheaper than the Aussie buck, so for Canadian money, you are saving quite a bit on the prices!