I reckonif the OP or anyone, especially NZ Elites or paid J passengers (maybe not for someone like me who's always use award tix on NZ!), could have them for free if ask the FAs politely - I am sure NZ is happy to give away something worth in 2 digits to customers paying 4 digits for their tickets!

Otherwise ask FAs (or even better, in-flight concierge) how much they cost to buy or where to buy them. I'm fairly confident that NZ won't mind business class passengers get something small like salt and pepper shakers for free - it's not like asking for the whole set of crokery or a business premier seat/bed I would be interested if they had a garage/hangar sale of "preowned/used" flatbed seats!