You can’t wrap your head around it because $76 per 13 pound bag is ridiculous. For that cost, you could pretty much get your dog raw beef or chicken from the supermarket every single day and still save money.
I second Fromms. Great stuff. Not really cheap ($70ish for a 25–30 pound bag) but it makes a visible difference to the dog’s coat. Grain-free formulas if you need it and quality ingredients. They also have the same buy X get one free deal.
Also, don’t make the assumption that grains are bad. Some dogs don’t react well to it (not a real health issue but it can make them too excitable and/or give them runny noses) but others are fine. If your dog has no problem eating grain, then save the money get don’t bother with grain-free.