cheap protein sources

For 100 calories:

canned lite white or albacore tuna (about 3 oz.) - 22 g
fresh raw tuna (about 3.3 oz) - 22 g
egg whites (about 3/4 cup raw) - 21 g
white fish like cod, tilapia (about 3.5 - 4.5 oz. raw) - 21 g
Egg Beaters original (about 3/4 cup and 1 Tbsp raw) - 20 g
boneless, skinless chicken breast (about 3.33 oz. raw) - 20 g
Unjury protein powder (one scoop) - 20 g
shrimp (about 3.33 oz. raw) - 19 g
lite firm tofu (about 7 oz. raw) - 18 g
salmon (about 3 oz. raw) - 17 g
1% milkfat cottage cheese (about 2/3 cup) - 17 g

A lot of the "traditional" protein sources that we think about-- milk, beef, cheese, yogurt-- have varying levels of fat and other nutritionals in them that bump up the calorie count for a specific serving, making them, although excellent protein sources, not on my list of "cheapies." Feel free to research and enlighten me to others. I do a lot of my nutritional research using the huge, free database at CalorieKing.