To give you an idea on the amount of savings possible look to this example....

My mother-in-law adopted a German Shepherd that was headed for euthanasia that day. She started her on "W4l-M4r7" store brand until I could get up there to take a look at her. Once I moved her to a high quality diet that was actually 3 times (or more) the cost for a same size bag the overall food bill went down. The pup didn't need as much kibble to get the nutrients she needed and the "full" feeling she wanted.

It may be counterintuitive, but QUALITY food that is more expensive will in the long run reduce your food bill. Unless you have a Siberian Husky like my wife's dog. She does not understand when to say when. Looks like a grey and white fluffy sausage with legs.