Right now Amazon is having a killer deal on diapers shipped FREE right to your door!
First join Amazon Mom if you are not already a member. This will get you 30% off diapers and wipes with subscribe and save.
Next choose your diapers and size, the best deal is on Huggies Snug & Dry Diapers, but I will be purchasing Huggies Pure & Natural Diapers (Pack of 2)
Make sure you choose the Subscribe & Save option on the right right under where you see Add to Cart. I always choose 6 months so that I have plenty of time to cancel the Subscribe & Save as there is NO obligation ordering this way.
Enter or choose your payment information, then review your order. On this screen there will be a place to enter a coupon/promotion code. Grab your November issue of Parents Magazine (or go out and buy one) and look for a 20% off diapers coupon (usually they are orange or yellow/green), enter the promo code and you'll score an additional 20% off.
Even without the coupon code the Huggies Snug & Dry Diapers will be significantly cheaper than Costco.
On a side note these diaper coupons are why some people get several subscriptions to Parents Magazine.