I just made myself a terrific turkey and cheese on sourdough with lettuce and tomatoes. I'd say buy basic sandwich ingredients from a fairly decent supermarket. It averages out to somewhere between two and three bucks a meal.
Also, Progresso makes some pretty damn good canned soups. You could eat one of those and some Ramen for poco dinero.
“It is a strange paradox that today’s central banks are generally staffed by economists, who by and large profess a belief in a theory which says that their jobs are, at the best, unnecessary, and more likely wealth-destroying. Needless to say, this is not a point widely discussed among respectable economists. Nevertheless, it is an issue worth pondering.”
George Cooper, The Origin of Economic Crises