This is a great site for getting cash back for diaper purchases.  You can get $1 back per pack 

The Caregivers Marketplace™ is the nation's first cash back program for anyone who gives, gets or needs care. Including babies and children. You can receive cash back on eligible products ( Huggies, Pull Ups and Good NIghts as well as gold bond lotions) that are not typically covered by insurance or Medicare – no matter where you buy them. The program is free and your information is always kept confidential.

To start getting cash back, just follow these five easy steps:

1. Enroll online (to reduce the processing time for your first cash back check).
   
2. Print a cash back request form.
   
3. Purchase five or more of the same or assorted products.
   
4. Complete the cash back request form.
   
5. Send in original receipts with your completed cash back request form.