I don't know where you can get them in Auckland but I have several old baths, fibreglass ponds and mussel floats in the yard which I just fill up with water and leave. They fill on their own with daphnia, mosquito larvae and other little critters. I have green water in a bath of goldfish so dump a bit of that in occasionally otherwise I don't feed them or anything. They slowly multiply and since I have few fish, and lots of containers, I have sufficient for my needs.
They can be fed on grass clippings, dried sheep poo, dried blood or dried yeast.
I have found they do not travel well and start to die after a couple of hours in a lidded container - I would put them in a 1kg peanut butter jar 1/3 filled with water. If I removed the lid every so often they were OK but keeping the lid on, despite the air gap, killed them pretty quickly.