Hi Chris,
We haven't moved yet, so I couldn't tell you for sure, but in my research Gandhi Appliances (
http://www.gandhiappliances.com/) seems like a great resource and possibly the best prices on large transformers and dual voltage electronics, and
http://www.world-import.com/all-transformers.htm also seems like a great choice. We will be bringing our Dyson vacuum, Vitamix blender, food dehydrator, water distiller, which are all around 1100-1300 W, and the salesman at one place recommended going for at least a 3000W, preferably 4000W, model. I'm debating whether to go for the cheapest, step down transformer, or for the more costly step up/down model with voltage regulator since I've heard reports about fairly frequent voltage spikes and surges in NZ power supply. We are probably going to buy one big 4000W box to leave in the kitchen, and 3, 50-200 W small units to operate other things in other rooms.
Regards,
David