If they are going on the Investor visa, then they will need several million dollars which will need to be invested for two years. The scale starts at $1m for those under 45 who have had 10 years business experience and goes up.
NZ doesn't seem to mind older folks staying for 6 months of the year, but they are reluctant to give them PR unless they have close relatives in the country. If you have got a couple of days free you could trawl through the immigration website. I know this is obvious but I keep forgetting there is more info on this site than just the forums - if you haven't done so already, check on this site's Immigration FAQ
http://www.movetonz.org/immigration.html
::):