If what Realdogs posted is correct I have been feeding the bottom of the barrel food. I thought beneful was good.
"plain brown food" is generally the way to go. The dyes and fancy shapes are just for your enjoyment, the dogs don't care
I feed the Merrick Wilderness Blend but I'm only feeding one dog so the cost isn't as important.
Buying in bulk or direct drop shipping to your house from the websites can cut costs also. Some companies have a "buy 5 get 1 free" deal.