If you use casein protein powder often and are looking to save some money, look into making your own Greek Yogurt. I love Greek yogurt but it's expensive as hell, almost twice as much as normal yogurt or cottage cheese. I always knew it was pretty easy to make, so I finally tried it out this weekend and I'm damn glad I did.
Half a gallon of milk makes about 2 - 3 cups of greek yogurt depending on how much you strain it, which comes out somewhere around ~60 grams of protein. I know milk prices differ, but I can get a gallon for about $1.40 here at Costco, so we're talking 70 cents for ~60 grams of protein, which is cheaper than even boneless chicken breast from a protein/$ ratio.