It looks like we can add Macadamia nuts to the list of niche foods (like vanilla and chocolate) that are experiencing increased demand beyond what can be produced.
South Africa is the largest producer of Macadamia nuts, so price news there will affect the entire market. It looks like in anticipation of a short supply Chinese buyers began buying larger quantities of the in-shell nuts, according to an article in South Africa's Fresh Plaza news site. The will have consequential effects on the shelled nut market and then on to all other products using the nuts, including Macadamia nut butter.
This is in contrast to lower prices that were experienced about 10 years ago in Hawaii because 10 years before that, lots of new Macadamia nut production was planted. The total amount of Macadamia nuts produced in Hawaii (47,000 lbs. last year) isn't enough to directly affect global prices, however.
Jansen, Carolize (2017, June 26). South Africa: Record prices for macadamias as demand exceeds supply. Fresh Plaza. Retrieved from http://www.freshplaza.com