Check out:
http://disboards.com/showthread.php?t=1378963 and the links provided in those posts.
Basically you purchase items at CVS that are ECB deals. You pay OOP for the 1st couple of transactions. My 1st trip was around $30-40. Then the ECB's print out on your receipt. You get 1 ECB per item purchased that qualified for an ECB. If you purchase multiples of the same item and there is a limit so read the small print, you will get 1 ECB for the total of those items purchased in a single transaction. So for example of this week, if you purchased:
2 aquafresh advanced (monthly deal limit 3) and
1 sea breeze astringent
you would pay those items (approx $10 OOP (out of pocket) and get back 1 ECB for 6.00 (2 aquafresh) and 1 ECB for $3.99 (sea breeze). These ECB's are good on your next transaction and have an expiration date of 30 days out. On your next order you put together you can apply the ECB's to it reducing the cost of that transaction by $10. Many people plan their shopping trips around how many ECB's they have so that they pay little out of pocket in subsequent trips. I try to limit my OOP expense to around the $2 mark. By adding coupons into the mix you further save money. Going back to the Aquafresh. It is already free AFTER the ECB. So by using a mfg coupon when purchasing the toothpaste you are reducing your actual cost by the amount of the coupon but they will still give you back the total amount of $2.99 in the form of an ECB, so now you have profited that amount and can use that towards other products. It is a little confusing the 1st couple times but people tend to get the hang of it pretty quick. Let us know if you have further questions after you read the other posts/thread.