Cindy
When I did this tour I took cash, credit and debit card and paid for all the trips in cash. It worked fine for me and of course you won't need money on the very long plane journeys LHR/Hong Kong/Auckland. I even changed my leftover HK Dollars to NZ Dollars on arrival in Auckland.
From memory, the trips involving planes can be paid by credit card in the relevant company's office which you get marched in to on the day of the trip.
Sylvia
PS. Can I have your autograph?!