Amazon has a new 20% coupon for Optimum Nutrition Gold Standard 100% Whey Protein Powder, Coffee, 5lb
Combine it with Subscribe & Save option to get another 5% off and free shipping.
The final price is $43.49 (or, if you have 5+ subscriptions this month, $37.69)
Coupon works on other flavors as well.
Note: this is a new coupon. I got the same deal on Black Friday - today it re-appeared again, allowing me to order another jar.