G'day, Rich. I have imported my Mason 53 to New Zealand
. I believe the cost to do that today would be 15% GST (goods & service
tax) + 7.5% duty (boat built outside of New Zealand) based on the value of the boat.
If you are an U.S. citizen and have your vessel documented, you can still keep it as a U.S. flagged vessel. This will allow you to sail into and out of New Zealand waters without obtaining Category 1 certification
that New Zealand flagged cruising vessels must have (annually if clearing in and out of customs).
There are no registration fees
for New Zealand cruising yachts to date, if you can believe that.
Let me know if you want any more detail. Cheers.