Amazon's Diaper Discount: Use Amazon's Baby Registry and they'll give you 20% off diapers for the first year. Add the Subscribe & Save options and you're up to 40% off. Serious savings. 2. Join TopCashBack. It's free and the savings add up fast. Vitacost is on there and it's often up to 6% cashback. It's easy to redeem as well. 3. Use Honey. Forget trying to look up coupon codes. Use Honey and it'll find the best usable codes when you go to checkout. I've saved hundreds. 4. Vitacost. No membership fee and there's always a coupon code. Use TopCashBack and Honey with Vitacost, and your diaper savings are huge. 5. Cloth diaper. No doubt — if you truly want to save money on diapers, consider cloth diapering. You can even find them used. My faves are the all-in-one options (buy one size and it's good from newborn to potty time).