Besides the big stores giving the 10th bag free. Remember the free one is of the smallest size bag you bought. So if you needed to by a small bag to get by, don't let them scan your card, or use two cards one for small bags and one for big bags.
Anycase.... petsupermarket sends me a 5$ coupon in an email once a month off purchase of 20$ or more.
So I spend about 25$ on a bag a food about every month or so. Kiani's only 35-40lbs so she doesn't eat as much. I've also notice I don't have to feed her as much as the cheaper stuff.
I feed her Merricks brand which is rate 5-stars on that review website. I've been really happy with it since it started showing up in petsupermarket stores. Originally it was one of the few treats she would eat. Then they came out with the canned foods, but I wasn't about to put her strickly on canned foods. I checked thier website and saw they had dry food as well, but it didn't show up in the stores for months later.
I had her on purina one, but with her long coat she needed something a bit better, and she kept getting UTI's, but I don't know if it was from the food or not. I haven't had any problems since putting her on Merricks. And I only spend about 25$ for a month's worth of food. She eats much cheaper than I do....
We were really poor and kept her on the purina, but now that we're poor again, I haven't found it to a problem to keep her on this food. I buy small bags when I need to and always use the 5$ coupon when I buy the 15lb bags. They sell the 50lb bags now, but I do better to buy two 15lb bags using a 5$ coupon on each.