Beefy, there is work all over New Zealand, but you will need to get a job with a company that has accreditation to employ overseas workers unless you have immigration status.
There is work pretty much all over both islands, and opportunities if you have a work visa. All the big cities, especially Christchurch because of the earthquake, are looking for for eligible and qualified scaffolders.
Pay rate is generally between $30-35 NZ for an advanced.
Trademe.nz and Seek.nz are good websites for job adverts.
Hope this helps.