Believe it or not, at Costco, a box of Huggies ($49.99 for 228ct) and a box of Costco Brand ($47.99 for 212 ct) cost about the same when you divide number of diapers by cost of box. For size 3, you pay about $.22 per diaper.
Smaller value boxes cost about $.30 per diaper (even bio-friendly Earth’s Best brand at Babies R Us $22.99 for 76 ct), and Huggies Snug and Dry Mega Pack at Babies R Us $17.99 for 60ct). Store brand starts to pay off at this size, a Super Mega box of Babies R Us Supreme diapers ($24.99 for 116) comes in at $.22 per diaper.
Best value seems to be Babies R Us store brand Ultra Value Box of 144 diapers ($24.99) comes in at $.17 per diaper. But as I have not tried these diapers, I cannot speak to their quality or how they would hold up overnight. I just tried out CVS Supreme store brand of diapers (on sale $9.99 for pkg of 27, not the best value at $.27 per) and they held up during the day and at night with at least one change in the middle of the night. But last night my son slept through the night (can I get a hallelujah?) and when I changed his diaper, a flood of pee came out of either side from compression. His PJ’s were soaked. I am a little more than worried about the flight home today with him sitting in my lap drinking juice or water the whole hour and a half!
All of these costs (except CVS) are for non-sale, non-coupon costs. Coupons are money in your pocket. They do not take much time to cut out and bring with you. Get a coupon envelope and stick it in the bag you are most likely to take into the store with you. Be organized and only cut coupons for the brands you use. Make sure you understand the deal and if it is worth it or not (often times at Costco, you also have to buy the box of that brands wipes as well and they are not cheap). Combining an ad sale price with a coupon is pure gold and you will drop your per diaper price a lot.
The absolute cheapest way to diaper your child is with cloth diapers (unless of course, you get hooked on the cute factor and start hoarding couture boutique cloth diapers like goodmama’s at $30-40 per diaper). Using flat fold or pre-fold diapers and covers is the least expensive way to do it. You can even make these out of old clothing you have or thrift store finds! Cotton Babies has a great article about this. If the problem you have is the cost of washing diapers (like I did when I lived in an apartment and had to pay $3-$4 per load to wash and dry in the coin op facility in our building), Cloth Diapering Bloggers has an article on using flats (you know all those cute but seemingly useless receiving blankets your well meaning but cheap friends gave you at your baby shower? yup, those can actually be used as flats, as well as burp cloths, changing pads, wipes, and a plethora of other things) and hand washing.
If you don’t get caught up in the “green trend” of having to use only organic or natural fabrics, you can get started with very little to no cost out of pocket actually. If you have a pile of old t-shirts/flannel sheets/receiving blankets for the diapers; a couple wool/fleece sweaters or blankets to make covers from; safety pins/snappis/velcro (or snaps and snap pliers/press) for fastening; a pair of scissors; a needle and thread (or sewing machine); a trash can with a lid and trash bags or an old shower liner; a washing machine or bath tub/sink/bucket; and detergent or a bar of laundry soap you can cloth diaper your child. If you are using wool, lanolin is necessary to help clean, care for, and waterproof it. You can make fitted/contours, flats or prefolds, and velcro/snap or pull on covers. Let me point you to the forum where I have found a wealth of info for making cloth diapers: Diaper Sewing Divas. There are a million different patterns and fabrics they recommend. Don’t get overwhelmed, just jump in using what you’ve got and sew up something!