Brian's right in that powders should be a supplement, not the main source of protein in a diet. Tuna, chicken with the skin on (you can always get rid of the skin and bones later) etc. are cheap sources of good quality protein.
It's not exactly the same as getting protein from nuts. Amino acid and what not are different, but the philosophy still holds true.
And if you don't think kettleball squat cleans are difficult, I say, step up to the med-ball
- CJ Kim