The New Zealand dollar varies in each country, however, in comparison to US dollar, there is not much fluctuation. You can buy paper currency in your country either in US dollars or NZ dollars and exchange them here. All credit cards are accepted in shops. Here other options:
CARD INCOME VISA TRAVELMONEY: It is a pre-paid card international, rechargeable into dollar or euro and used for purchases and withdrawals in the local currency of destination. It is safe and convenient in which provides replacement of the card in case of loss or theft.
TRAVELERS CHECK AMERICAN EXPRESS: It is easy and safe. It is accepted as money in thousands of establishments or can be exchanged at banks in New Zealand, often without charge. There is a reimbursement on the event of loss or theft.