Amazon offers the Optimum Nutrition 100% Casein Protein 4-lb. Tub in Chocolate Peanut Butter (pictured),
Cookies 'N Cream, Banana, or Creamy Vanilla for $49.77. Clip the $8 off coupon (located directly under the price) to cut it to $41.77. With free shipping, that's $41 under list and the lowest total price we could find. Each serving contains 24 grams of protein.