Volumes 1 - 20 is on sale at Gould Genealogy & History for A129.50 at the moment. I just checked the currency exchange and its NZ$165.09. Not bad!
I'm tempted but since I've effectively finished my New Zealand trees, it would be a bit silly for me to buy it.
1935 was part of the depression years when there was a lot of movement of people as they desperately tried to survive, there were work camps and swaggers and families moving in together, or moving to the cities.
Gould Genealogy has other electoral years for sale as well.