Protein powder should only be used as a substitute if you cannot afford/have time to prepare protein rich foods such as chicken, steak, etc. While high protein foods are more desirable, protein powders are mostly necessary. There is absolutely no difference in different powders, except for calories, which can be made up by mixing them with whole milk. So go with any powder man, whatever you can find that is most affordable. I've found that at Bi-Mart stores you can find Muscle Milk Pro Series which contains 50 grams of servings for $26 in a 12 serving container. Good luck on your fitness goals!