Here is a general guideline you can use to calculate whether or not a diaper sale is a GOOD sale...
Size 1--Aim for $0.11-$0.13/diaper or lower
Size 2--Aim for $0.15-$0.17/diaper or lower
Size 3--Aim for $0.19-$0.21/diaper or lower
Size 4--Aim for $0.22-$0.24/diaper or lower
Size 5--Aim for $0.22-$0.24/diaper or lower
Size 6--Aim for $0.28-$0.30/diaper or lower
If you can find your diapers at these prices, or lower, with loyalty bonus points offers attached to them as well (ie Shoppers Optimum points, Club Sobeys points, etc) then you're ahead of the game!
These numbers are based on sale prices plus the use of regularly available coupons. There is always the opportunity to get higher value coupons from the company, and find great clearance to get diapers cheaper than the above listed prices, so do keep your eyes peeled!
But for regular day to day availability, this chart should help you do the quick math and see if a sale really is as good as it seems!
HAPPY SAVING:)