There aren\'t many single-DIN navigation systems to choose from (or car navigation systems available full stop) in NZ, but there is the Alpine IVA-D511EBT, which has a slide-out 7" touchscreen. Retails for $2499. However, it doesn\'t come with built-in navigation: you also need the NVE-M300P add-on module, which is another $1200 or so.
Something you might like to consider is that, like portable in-car navigation systems, most models available in Australia also include NZ maps. If you\'re serious, buying from there and getting it shipped over may save you some money.
Cheaper yet, get a standard head and spend $3-500 on a Garmin or TomTom portable unit with free lifetime maps and save yourself $2-3000 now and $250 every time you update the maps! That\'s what I did, and just binned the Japanese double-DIN nav paperweight.