Nikon d600 for $1580...vs $2300!
Buy local. Nikon Australia WILL NOT provide support or warranty for grey market items. And neither will their authorised repair agents (AFAIK). They will, however, do repairs for a fee. Which is a better situation than a few years ago, when they wouldn't touch grey market at all. (Lenses are a different matter, I believe, as Nikon warranty them worldwide. Odd, but that's the way it is.) $600 is a lot of money, but when it means contacting an overseas organisation, paying for shipping overseas, waiting for weeks while your camera is (hopefully) being repaired, then waiting for it to (hopefully) be returned in one piece, I'd pay the extra and be happy. But that's me.
I've read good and bad reviews about Mack warranties, and personally, I'd stay away. (I've read lots more bad ones than good, which isn't scientifically rigorous, I know.) However, paying extra for a warranty that is a pain to access makes me grumpy, so I'd buy local.
'Stores' are places where things are kept. 'Shops' are places where things are sold. Buy from a shop, not a store.