Buying an Apple Mac in USA

Macs have universal power supplies/adapters and will work worldwide. All you need is the correct AC plug adapter for the US and/or NZ. Apple has a nice kit called the Apple World Travel Adapter Kit that contains all the worldwide plug adapters in one box. It's completely worth the $29 USD price.

The only thing he might need is an AC plug adapter for the power supply if you use a different type of AC plug than in the US. The power adapter is a "universal" supply and operates from 100 as well as 240 volt power so only an outlet adapter is needed.

I'd buy it in the US. State and local sales taxes can exceed 10% but I don't believe they will exceed NZ's 15% GST. Some states have no sales tax.

When he returns to NZ he may have to pay import duties; I don't know. Some countries are more stringent than others. Be sure to keep the sales receipt as it is not easily replaced.

The Mac will work in NZ.