New Zealand has a stable economy, quality public health & education systems, it’s very safe with low criminality and solid annual growth rates.
Living costs in New Zealand are very similar to Australia.
Prices vary depending on the area you are planning to live in, your lifestyle and your capacity to plan and save. For example, living costs increase if you eat out daily and if you have a car and choose to live alone. You should also take into account the city in which you choose to study, becuase rental prices are not the same in the centre of Auckland as in a smaller city like Napier or Queenstown.
According to New Zealand Immigration the average yearly living expenses for a university student is estimated in $NZ20,000. New Zealand university websites also list the average living costs for students (accommodation, electricity, water, gas, telephone and internet services, food, transport & entertainment)
The NZ dollar = 0,59€ (June 2016)
Link of interest: Mercer 2015 Cost of Living Rankings