EDIT: This deal is not limited to Pampers. You can get a steal on any diaper Amazon sells (Huggies, Luvs etc)
If you live in the US, and have kids, DO THIS! (Unsure if it would work etc in Canada).
Sign up for a Amazon Moms account on Amazon.com. This will give you free 2 day shipping on everything you order! Plus additional discounts. For example, I have been buying Parents Choice (Walmart brand diapers) for Grey, they are 13.67 for 82 size 4 diapers (coming out to 17cents per, but that is not including tax). But they will leak overnight if they get really wet, so sometimes a middle of the night change is needed.
With my Amazon Moms account, and signing up for a Diaper Subscription (you can have it set automatically for 1, 2, 3, or 4 months and cancel at any time - I chose every 2 months). I am now getting 140 count of Pampers Dry Max size 4 Diapers for 28.56 (no shipping, and no tax online!), which comes out to 20 cents per diaper. This is a little more than I was paying, but for a WAAAAY better diaper (I personally consider Pamper Dry Max to be the best ones out there). So the price vs the value, can't be beat. Plus, I will never have to buy them any more, they will be delivered via UPS to my door! Super bonus. I will see how quick I go through them, I may need to up my subscription to once per month, but I doubt it...
They have all kinds of great deals. I ordered quite a few Christmas gifts from here, and with no shipping? Can't beat this deal!
It will only take a few minutes of your time, but for brand name diapers, you cannot beat this price, I would pretty much guarantee it!