Costco.Is it worth visiting if you are not a restaurant/cafe owner or have a big family ? 

Costco New Zealand. Wholesale store.
Just a private opinion after we visited this iconic bulk food store.
Food-wise New Zealand Gilmours is better, they dont charge you membership fee, have better variety of quality food products, they sell alcohol and staff is not as fussy...Decide for yourself.
By no means the intention was to create a counter-marketing campaign.