What you need to do is break down the cost per serving and go that route. I always remind people you cant look at just the TOTAL cost.
Take tuna, eggs, cottage cheese, protein powder, lean beef, chicken, turkey, and what ever and figure out what it is per serving.
For instance if you buy a protein powder for $45 and its 50 serv, what is that per serving? 90 cents per serving. BUT also look at the protein content per serving.
While eggs are one of the best sources, are they the cheapest? Is that tuna the cheapest? You will have to look at all of this.
Now for the above I was being high.
You can get a tub of Optimum Nutrition's 5lb Whey Protein for about $39+ shipping which is about $5. So $44 and 77 servings.
That's 57 cents for 24g protein/serving.
A WHOLE egg has 6g protein and eggs on sale here are now about $1.50 for 12 That's 12.5 cents per egg. BUT remember there is only 6g protein per egg and a little less if you take out the yolk, because there is some in the yolk. Roughly 2.7g
So if you just do the white, then lets just go with 4g for kicks. You'd have to eat 6 egg whites to get 1 scoop of whey protein.
12.5 cents x 6 is 75 cents per 24g protein.
So as you can see, the whey is cheaper. Again eggs have gone up tons in price.
Now the best thing to do is get a VARIETY of protein in the diet and not to settle on just one. They all have their places. I just had 5g that came from my Oatmeal. Am I going to count it? Sure as heck I am, because it is another form of protein. Now I dont get all of my protein from Oatmeal obviously, but if I end up eating a combination of say 15g from Oats and rice, its still protein and has its place. But I make sure whey, casein, and egg are also in there.
I know it may take some extra time, but you need to do the math to find what you can afford. Tuna is good, because usually you can get it for 50 cents and it will give you about 32g out of a 6oz can.
Also look at Peanut butter as well. I can get a jar of Natural Skippy PB for about $1.97 That's 7g per 2Tbsp and about 13 serv per container. You are also getting healthy fat as well.
Though the protein in some items are not what we call complete protein sources, it doesn't matter if they are used with others. For instance PB is high in glutamic acid at about 1.6g per 2Tbsp