Get yourself some glass bottles, or any bottles. If its not obvious, write the weight and volume* on the base. Take the bottles to the same bulk food and whole food stores mentioned in the Bulk food stores article, and try your luck.
*Some stores use weight, some use volume, they might want to weight it for you too, but can’t check volume in store – that’s a trick for young players.
ecostore are actively building a refill network through out NZ, check out their refill stations page (makes my heart sing!). In addition to the bulk and whole food stores they are also getting into in environment centres, community recycling centres, anywhere they can. They also take back and REUSE their largest containers, which I think are 20L. Products include detergents, laundry liquids etc.