You can find a retailer on their website -
http://www.bluepearls.com/
Be warned! They are very rare, so expect a little sticker-shock.
Also, their website has a lot of great photos. I can't tell you how accomodating and friendly they were. I want to go back to New Zealand soon. Two days was just a tantalizing taste of one of the world's most diverse countries.
Cheers,
Blaire