As per usual, Amazon has a $5 book discount. $5 off any book priced at $20 or more using the code: NovBook18 at Amazon.com
Not sure if it works on Amazon.ca but I wasn't able to find it the same way on the .ca site.
Edited to add terms:
1. Enter promo code NOVBOOK18 at checkout to qualify.
2. Offer expires at 11:59 p.m. (PT) November 25, 2018.
3. Offer only applies to products shipped and sold by Amazon.com (look for "Ships from and sold by Amazon.com" on the product detail page). Products sold by third-party sellers or other Amazon entities will not qualify for this offer, even if "fulfilled by Amazon.com" or "Prime Eligible".
4. Offer does not apply to digital content.
5. Offer good while supplies last.
6. Shipping charges and taxes may apply to the full value of discounted and free promotional items.
7. Items must be purchased in a single order and shipped at the same speed to a single address.
8. Offer limited to one per customer and account.
9. Taxes, shipping and handling, and gift wrap charges do not apply when determining minimum purchase amount.
10. The maximum benefit you may receive from this offer is $5.
11. Amazon reserves the right to modify or cancel the offer at any time.
12. Offer is non-transferable and may not be resold.
13. Offer discount will be allocated proportionally among all promotional items in your order.
14. If any of the products or content related to this offer are returned, your refund will equal the amount you paid for the product or content, subject to applicable refund policies.
15. If you violate any of these terms, the offer will be invalid.
16. Unless an Amazon Gift Card is the stated benefit of the promotion, promotional codes (including those placed directly in accounts) may not be redeemed for Amazon Gift Cards.
