Muscle Gauge Nutrition, the brand with the cheapest protein on the market, looks as well as price. Are currently running a 20% off special on any order over $50. When buying direct from MGN their supplement prices aren’t that bad so this 20% does go a long way. The biggest bargain of the bunch is the 77 serving American Protein Isolate. Regularly it goes for $52.14 but with the coupon code ‘HOLIDAY‘, it drops down to $41.71. Just a buck away from that magical $40 5lb mark.