Don't let price be your only guideline in choosing a service provider. Most local providers' connections to the Internet have traditionally gone through the University of Waikato's international Internet gateway, NZGate. NZGate, and now Clear and Netway, operating out of the NZIX, charge service providers based on data transmission volume, so these providers will pass these charges on to you, either directly or indirectly. Volume charging is unusual, and New Zealand is perhaps the only country, outside Chile, that has widespread Internet volume charging. Thus volume charging has been the standard method by which most New Zealand Internet service providers have charged their users.
Many providers also have different off-peak and peak rates.
Many local providers are changing to time-based charging, and some even charge a flat rate per month. Many also offer a choice of all three types of charging, and combinations as well. Different users have different usage patterns and different needs. Pricing, service and support, stablility, speed and reliability are just a few of the many factors to consider before making an agreement. Fortunately, changing providers is not terribly difficult, although there are factors to consider if you are planning to jump ship often.