Model: WDS500G3X0C, currently $153 @ PB Tech.
Few ways to go about doing this. I have a $5 promo credit on my account that prevents me from giving a proper overall NZ price. I've added US$5 to the overall price in both equations.
Method 1) US$10 off order over $20 via App (Need USA address in address list & targeted)
US$59.99 + $5.38 shipping + $5.04 GST - $10 app first purchase = US$60.41 approx
Method 2) US$10 off order over $60
add this item to cart
US$60.56 + $11.10 shipping + $8.49 GST - $10 NZ10 = US$70.15 approx
Maybe use a United States address generator if buying using app discount. Activate app deal via phone browser so it opens the Amazon US app.
Thank you for the effort and the calcualtions, very good info.