Some more notes:
I shared a campervan for the first 4 days in NZ (was there 3 weeks), and didn't find it much better for accommodation. It was a bit difficult to find places to freedom camp, so we had to use a lot of camper van parks, which are actually kind of expensive for what you get! For example $16+ PER PERSON just to park the van in a spot, showers costing extra, where you can get a dorm room for $20-$30 with full kitchen, shower. Do not underestimate the cost of petrol… it was cringe-inducing.
Busses aren't that expensive, but sometimes their locations and schedules make it difficult to go certain routes. I used mostly NakedBus, and another company whose name I forget. It wound up being cheaper to take the bus and stay at hostels.

