In an effort to not re-invent the wheel - this time I will simply recommend that you check out the great deal that Frugal Living NW has posted on diapers from Diapers.com. This is a really good deal!
Before heading over there, the only thing I can add is to start at http://www.ebates.com/ instead of Diapers.com as you'll get up to 4% cash back from ebates.
Click here to get the details. DO NOT click on the $1.50 eCoupon on Diapers.com as it messes up your total and is hard to get rid of.