The one important fact to take into account when talking about cost of living etc. is having some idea where you intend settling. In cities like Auckland and Wellie you're talking about higher costs for most things whereas in the more provincial towns and cities, it probably won't be so high. Also it depends on what kind of lifestyle you want to live and whether, due to your circumstances, you're prepared to cut everything to the bone to survive whilst you look for the all-important job. Everyone is different and has different needs.
As an exercise, how's about taking a look through the
Master Website List . In there you'll find property sites where you can see how much the kind of rental you're looking for will cost. There's car rental or car dealers and even online food/household sites where you can 'do' a weekly shop. It won't give you all the expenses you're likely to meet, but it's a start and you can tailor it to suit your own particular needs. I hope the links are still current as they have a tendency to become defunct over a period of time, which is a tad annoying.
Perhaps others can chip in with an overview of their typical expenses for things like insurances, rates/council tax, phone bills, electricity, nursery care etc.