We bought our nectar feeder at the shop on Tiritiri Matangi Island. I have also seen them for sale at other DOC visitor centres. You could try contacting DOC for where to buy one near you. You just make up the sugar solution and put it in an empty plastic bottle, then invert the bottle into the plastic feeder, which has holes for the birds to put their beaks in. Clever people could defintiely find a way to improvise this I think.
As you can see above, the sugar solution needs changing daily and it all needs cleaning regularly.
Not much action as yet - 2 silver eyes earlier on. Nothing else as yet. I'm dispatching J to buy monkey nuts tomorrow, as I know kakas like these...