I've spent years looking for decent and economical vegetarian sources of protein. I finally settled on seitan because it's so cheap and easy to make. You can make your own seitan from vital wheat gluten and nutritional yeast with flavorings. The recipe for seitan is extremely versatile, and you can formulate it your own taste. It's easy to make once you assemble the ingredients, but it takes a little practice. I'll be happy to share my knowledge if you're interested.