Rice is insanely cheap and easy to make, and can be paired with almost any protein source. I have a simple rice cooker, and can make a bunch of rice at once. Super easy.
Then for a protein source, ground turkey is very cheap. Often $3/lb, sometimes even less. I’ll cook up to 3lbs of it at once. Good for 6 1/2lb servings or 12 1/4lb servings. Ground beef is the same deal. Chicken breast is super cheap too if you buy from the right place.
Just mix the turkey or beef with the rice. For chicken, cut it up and mix it with the rice. You can do the same with hard boiled eggs too. Make a bunch, then dice them up and throw them in with the rice.
All of these meals are very cheap and allow you to make a lot at one time. From there, you can add some vegetables if you want, and some sauce, etc.