Hi there from a fellow Kiwi, who can confirm that Swappa bottles are the business for homebrew! They are absolutely ideal, plenty strong, made for refilling, they are the money, and best of all a source for cheap bottles. Just get all of your mates around to drink the swill that comes in them, or buy their empties off them for $10 a crate!
For all other (non-kiwis) who are interested, a swappa crate is an old-school wooden crate of 12x 750ml refillable bottles that the major brewers sell their bulk brands in. You get 9 litres of (not very good) beer for about $40. Then you take the empty crate back to the liquor store (or "bottle shop" if you're old-school) and "swap" the crate of empties for full ones at a discount. Apparently it's a huge PITA for the brewerys, and they hoped that they'd die out in the 90's, but it didn't happen.
For an example of a swappa crate required viewing is the movie "Once Were Warriors"