The requirements are here on the INZ website.
http://www.immigration.govt.nz/migra...quirements.htm
And there's further information here.
http://www.immigration.govt.nz/migra...onsanswers.htm
As you'll see, there's no exact amount mentioned as being required for the business, presumably because businesses vary so widely. The only mention of a sum of money is about support for your family.
Funds
What amount of funds do I need for maintenance and accommodation, in addition to the capital for my business?
This will depend on your location, living arrangements and lifestyle but between $60,000 - $100,000 per year is a rough estimate. You should not rely on profits from your business for this purpose.