I am only posting this, in case you were not aware, but Beneful is packed with corn syrup (sugar) and corn... literally in the top 5 ingredients. I wouldn't feed this to a working dog, but that's IMO.
We sell Canidae at my work for $30 for a 40 lb bag, it's a really awesome kibble with no corn, no soy, no fillers, no by-products, and a high meat content (the top 4 ingredients are all quality meats). It's all-stages, so it's great for dogs of any age. Many, many customers with working dogs buy this because it truly is cost-efficient for the quality. I've looked it up, and you'd need to feed 2 to 3 times the amount of Beneful than you would Canidae and other quality kibbles.
Sorry to get off-track, but, I just wanted to put that out there. Mordy's cost comparison chart is extremely informative, as well!
About the Raw debate, I will not get into that, mmkay. =) I definitely do feel that a prey-model or BARF diet is much healthier, with or without supplements. But, based on the research I've done, I feel the need to add sources of certain nutrients that are not found in most grocery store or butchers meat, as it is in the wild. Not everyone agrees with that.