Right now Amazon has Seventh Generation Size 3 Diapers, 76 ct for only $16.79.  Here is what you will need to do:

$20.99 Seventh Generation Size 3 Diapers, 76 ct
20% off with Subscribe and Save & Amazon Mom
Net Price $16.79

Free shipping is included with the subscribe and save membership and can be canceled at any time.

This will ship for Free with Super Saver Shipping with orders of $25 or more. You can upgrade your membership to Amazon Prime and get Free 2-Day Shipping.

Disclaimer: This post contains a link to an affiliate. See my Disclaimer Policy for additional information. Prices are subject to change without notice from Amazon.com so please verify the purchase amount before you order.