When I was going to college, working two jobs to pay my way, I bought a house. Couldn't afford to eat much. Weekends to Mom and Dad's to eat and scrounge leftovers, but during the week....
Spaghetti ($5 was at least four days worth of lunch and dinner. Had to buy the cheap no meat, no name, sauce though).
Kraft Mac and Cheese (Could always find somewhere they were on sale 4 or 5 for $1).
Balogna on sale. Bread on sale. $2 = 10 sandwiches.......