I just checked a book ( The Ministry for the Future by Kim Stanley Robinson in paperback ) for shipping to New Zealand.
Book Depository is $NZ 21.19 total. Including shipping a NZ Tax (GST). Discounted from $24.77
Amazon is $26.27 for the book, $24 for shipping, $7.50 for tax and $1.30 for "Exchange rate guarantee fee". Total is $NZ 59.27 or almost 3x what Book Depository wanted.