Right now, you can take advantage of free 2-day shipping when you buy Pampers or Luvs from Amazon.com.
Diapers sold by Amazon.com ship for free with 2-day shipping. To take advantage of this offer add eligible diapers to your Shopping Cart and select 2-day shipping. Your 2-day shipping cost for diapers sold by Amazon.com will then be deducted from your order total on the final checkout page.
While the prices aren't the best I've ever seen, they're decent, and the 2-day shipping is a huge convenience for new moms and dads!
Note that the page I linked to only shows select sizes. Click on the brand and diaper “style” you like and you should be able to choose different sizes.