As far as I know, the only turtles in NZ are Reeves, Red Eared and Snake-neck. Tortoises are Hermann's and Mediterranean Spur-thighed (Greek variety).
Red Eared Sliders and Snake-neck turtles are sold on Trade Me a bit.
No licenses are needed for any of these. Look at the New Zealand Herpetological Society for a list of reptiles and info on regulations etc. I have noticed the list is missing some reptiles that are available in New Zealand, and I hope my list is incomplete too!