If you haven't signed up for Amazon Mom (caretakers of small children qualify) in the past (try, you never know!), you are eligible to sign up and get FREE shipping on qualifying purchases. It's a 3 month membership and then it will cost $79. Be sure to mark you calendar, to cancel, if you don't want to continue.
You get free 2-day shipping on everything that qualifies for the Super Saver Shipping. (It's most everything that isn't sold by a third party. Even some of those participate!)
As a Amazon Mom member, you also get 20% off any diapers and wipes you order with "Subscribe & Save." (See link for details on getting a code.) Basically, you schedule shipments, but you can cancel them at anytime. Reminder emails are sent before the shipment goes out. This extra percent off on diapers and wipes is for a limited time, through September 15th. I think the 3 months of free shipping is good most anytime.
Check out their diaper prices to see what you think. Sharon says she's getting Huggies for about 15.6¢ each for size 3. Not bad, for getting them shipped to your door and not having to wait for the perfect sale.
Also note: If you are a student who has a .edu email address, you can get Amazon Student for FREE also. You get shipping benefits for 6 months! After that you're billed $39 for up to four years. Cancel, if you don't want to continue. Mark your calendar!!
(Thanks, Sharon — mother of twins who goes through a lot of diapers and wipes!) :)