So I would use the ECBs I earned for free from other products and then "roll" them into diaper deals. Then I could submit those Huggies receipts to Caregivers Marketplace and receive cash back from them, in essence getting paid to buy diapers.
There's an easier way though. There's a company called Arquest. They organize diaper studies. Currently they are looking for children who wear size 4 diapers. The process is very simple. All you need to do is call them, provide the age, weight and sex of your child and if there's still space available, they will FedEx or UPS a package of unmarked diapers for you to try for a week. These are often store brand, but not always. You use them for a week, fill out the questionaire they provide and at the scheduled time you determine they will call you and ask you to read your questionaire answers to them. Then they mail you a check for $10. So--you get a free bag of diapers and $10. Not too shabby.
If interested, call today. I think they are starting the sizes 4s next week - 1-888-342-7372 ext 634 for boys (Cheyla), and ext 646 for girls (Georgia). Give your name, number, size your child is wearing and they will call you back.