Free delivery with subscribe & save, or $39 spend/prime if you don't want to subscribe & save.
Thanks to mrfather for the heads up.
How to get free subscribe & save delivery without prime?
Click on "First Delivery on 'Day Month'" and ensure "Get it with your next Subscribe & Save delivery, with 10% savings and free shipping." is clicked when selecting subscribe & save; if you don't have prime. You can also select your subscribe & save date here. Once your item has shipped, it's safe to cancel your subscription here.