Just a heads up, the $25 credit that many of us got from buying the google home back in December expires in a couple days on 1/31. I just picked up the Chromecast 2 for $10 using it with free shipping.
Its a unique code that you apply at checkout. If you expand "Promo code" you should see something like this if you are eligible. You can only apply one code.
$25.00 promo code
YOUR CODE HERE
Exp Jan 31, 2018
Note: This is for Walmart on Google Express Orders.