Tuna (in water) is probably the cheapest form of protein (after all, that WAS the original question right?). I mean, ounce for ounce, pound for pound. Plus it has Omega 3's which is also a plus. But don't go gorging yourself with it at every meal. Just like with anything, excess is not good.
Having said that, whey protein isolate is also another inexpensive source if you're looking in the right place. NOT GNC. NOT some Super Duper Max Gainer Miracle Supplement X5000 - I would STRONGLY recommend against these proteins powders with Arginine added, Creatine added, etc. etc....NOT because those added components are bad, but because the QUALITY of ingredients AND the QUALITY of the ingredients are just horrible. Remember, these are BUSINESSES. Companies. What matters most is the bottom line. Profit. Money. Period. If they can get away with using less or lesser quality ingredients and still have the ingredients label say "contains X", then they will do just that.
If you want creatine in your protein drink, then add it yourself. If you want arginine or ornithine, then add it yourself.
My nutritionist has opened my eyes to so much in this category. With changes in my nutrition ALONE, I have dropped 6 percentage points of body fat, shaved .5 seconds off my 40, and increased my standing vert by 3 inches. It really is amazing what the body can do when it is fueled properly. And remember, "Fueled properly" means via nutrition FIRST AND FOREMOST! Supplements ARE NOT a miracle and will only work properly with a proper nutritional foundation (hence the word "supplement" aka "in addition to" not "instead of")
I get all my stuff from Purebulk.com - NO I'm not an affiliate and I don't get any profit from promoting them. It's just awesome pricing for pure ingredients.
Enter coupon code fffitness for 5% off. Again, I DO NOT get anything for that. They love my sports nutritionist and have hooked him up with that code for his clients as a courtesy. I don't think he gets anything out of it either. I've asked him before and he said it was cool to share the coupon code so......check it out for yourself.
hahaha!
you don't run faster or jump higher because you are "properly fueled" 
The fact that you would make that statement...frankly it shows that you don't understand the first thing about nutrition, exercise or performance enhancement.
Nutrition is EVERYTHING. And being "properly fueled" makes all the difference in the world. Would you put lawnmower gasoline in a Ferrari? Of course not. Would you even put the low octane car gasoline? Nope. Would it still run? Sure. Would it still be fast? Yup. Would it be as fast and have as much acceleration as if it had the proper fuel? NOPE!
Would an athlete be as fast or be able to jump as high if they didn't have their nutrition in check? NOPE!
If you don't know and understand that then you need to go back to the drawing board. I don't say that as an insult, but rather as an encouragement. If you don't understand this most basic principle, then the advances you would see by getting your nutrition down to a science would be amazing. It's simple nutrition/exercise/biology 101- your gains don't come from your workouts. Workouts is how you break your body down...and you break your body down for one reason and one reason only....so you can build it back up!! The way it builds back up is by what you feed it and how you rest/recover. Period. Again, this is the most basic and fundamental elements of training.
Ask any knowledgeable and experienced athlete and they will tell you that the most important element of their training is their rest. And I don't mean go ask some blog writer or internet "guru". I mean ask professional or Olympic level athletes or their trainers.
You spend MAYBE 7-8 hours a week working out. Even if you're college or pro and have multiple practices and games a week, you spend MAYBE 10-12 hours a week training. That leaves AT LEAST 154 hours of your week accounted for. This is where the magic happens. Tue vast majority of your time is spent AWAY from the weight room, field and court. Those who excel understand that THIS is where they should focus large amounts of their attention.
Some people are genetically gifted and can get away with not having strict nutrition and still have great performance. But even THEY would see a great improvement if they got that part of their life in check. But the rest of us who are athletes that aren't the Lebron James' of the world need that competitive advantage in order to compete. When it comes to proper nutrition, we absolutely NEED IT!
