...55 is the upper limit for most channels of immigration. Assuming you don't have family here, the most likely option is as a skilled migrant: Take a look at
http://www.immigration.govt.nz/pointsindicator/ and see how you do. Over 150 point is a given, 100-150 goes down to what immigration think is in short supply.
Alternatively, if you have the funds, look at the "professional investor" option - You'd need US$2.5 mil at the current exchange rate, see
http://www.immigration.govt.nz/migrant/stream/invest/activeinvestor/requirements/If you
don't make it past NZ immigration, take a look at Australia - under the 'Trans-Tasman Travel Arrangement' you should be able to live in NZ with Aussie residency, which I think is easier to get: I'd advise checking the details on that elsewhere, though. Or take a look at Tasmania, which was my second choice and seems a pretty nice place (for Australia ;) ).
Good luck... :)