Im sure maccaz will find some fault in this post and tell me to shut up and say I dont know what im talking about but heres a good one which is my go to at university bro.
2 cans kidney beans
1 can diced tomato
2 packets el paso chilli seasoning or similar (can be burritto seasoning etc dosent matter)
2 diced onion
tomato paste (optional)
cheap salami / bratworst sticks chopped up (optional)
frozen corn (optional)
Price for this would be around 15$ depending on what is on special but I like this meal because it is cheap and versatile, you can put it on steamed rice, in some wraps for burittos, buy 1$ corn chips and make nachoes, put it on toast with cheese. Will last you 4 days or more. Buy a plastic box and keep in fridge.
You can also put it in wraps with cheese and freeze them (makes a literal fucking mountain of burittoes), so when you are hungry and dont have time pop them in the microwave.
I make this usually once a week and am sick of it but its cheap and works.