I've seen quite a few deals for the Seagate 18TB drives at around the $650 mark. The linked drives are much cheaper - at around $500 inc shipping. Have similar specs to the Seagate drives - 5y warranty etc. No having to shuck drives either.
I think the reason for this is that most overseas stores charge in USD, which is strong atm - whereas TradeInn is in Euros, which the NZD is still decent against.
Best thing is that TradeInn doesn't charge GST, so if you keep it under $1000 per order you shouldn't get charged with GST at the border either. I'll give you a hint - if you buy two at the moment it comes in at $999.97 shipped - 3 cents short of the GST level.
I ordered a few a few months ago and they arrived fine - decent packaging, took about 2 weeks. I had to fill a NAS and this was the cheapest way.
Do you know if the CoINNs stack? I.e 1 drive is worth 291 CoINNs , would 2x be double on the same order? Technically then the more you buy the more you can save. If they do double then you can save $9.58 NZD on your next order of 2 while getting another $9.58 to spend