If price is an issue- Kirkland, Diamond brand large breed, and Canidae are good choices. I've fed the ALS Canidae to all my pups and they developed beautifully. If money gets tight, I'll feed Diamond... it's a good food for the price. Kirkland is also a good food if you have a Costco within reasonable driving distance (I don't).
Also look into Victor Dog Food.
At the price you are paying, at least move up to the Diamond or Kirkland foods, as they are far better quality than Science Diet, for similar/less cost.