Lonely Planet has a great offer right now, buy 2 books and get 1 free! Just add 3 books to your cart, and get the lowest priced book for free! Also, all orders to Canada over $40 USD ship for free via USPS.
I added 3 New Zealand guide books to my cart: one for the North Island, one for the South and a Trampling Guide. The lowest priced one ($19.99) was taken off and I qualified for free shipping, which is worth $16 to where I live! It is too late to order these books for my trip: but we are going with 2 guide books to help us plan and execute the best trip ever!
See terms and conditions hereif you are having any problems. I have never ordered from Lonely Planet before so I do not know if you will be charged duty or not. I do know that they are very well known for their guide books!