Soups! They can be made hearty or lighter, depending on how hungry we are. They can be made vegan or grain free or cow milk free. They can be made ahead for later use, saving not only dollars but time. And believe it or not, on top of the chance to use much healthy fresh produce. soups actually have a cooling effect in summer time: http://easynaturalfood.com/2012/05/12/summer-soups/
My go to cheap meals are spaghetti or pasta meals, tinned sardines, tuna, tinned mackerel with salads, stir fried meals using left overs, stews or casseroles, soups, salads(hot or cold), noodles and egg meals to mention a few. Hope these help.