I pretty much live off of beans, pasta, and tacos. I'm not the biggest rice enjoyer, but sometimes I'll have rice.
Tacos are especially good because they're so customizable, delicious, nutritious, and ultimately filling. Of course, you don't need a lot of money to make tacos either. Usually, I go with either refried beans (check and make sure they don't have lard when you're buying them), pinto beans, or black beans, and I'll put it in a tortilla with pico, lettuce, taco sauce, and maybe some rice and corn. It gets the job done, and all of the ingredients are definitely low in price.
Also, a bonus tip: if you're ever craving something with a "meaty" texture but do not want to dish out cash on expensive mock products, mushrooms will be your best friend, especially those portabellas.