I priced it out once, because I got way into dry goods earlier this year. a massive serving of rice purchased by the bag is like 12 cents, a belly busting amount of dried black beans is around 25 cents. there's also kidney beans, and a world of lentils. I prefer red lately.

straight up unflavored beans and rice is kinda buttcheeks, but there are several routes to go with it: creole/cajun, meijicano, cuban, etc and it's all just a nickle and dime worth of seasoning and actually buying a fresh pepper, onion, etc, which to be sure is gonna be a few bucks.

it takes stability and an investment of time, effort, and money (spices, equipment) to build up the kitchen infrastructure to support making "beans and rice" from scratch a few different ways or to holster few basic lentil-based curries, but they'll stretch meals way out. and, I dunno, even when I eat too much beans and rice, it's never made me feel like shit afterwards, lol.