If you will already spend $100 on diapers anyway, why not get a free gift card with it? This Target diaper promo gets you $30 back, which is (indirectly) like getting free diapers.

SPEND $100, GET $30: As of April 8, Target will give you a free $30 gift card when you spend $100 ... find out as they're shopping for the diaper raffle. Whatever your need for buying diapers ...