Mixed bean salad, tuna salad or egg salad (either sandwiches with lettuce and tomato or on top of lettuce with tomatoes and cucumbers on the side), grilled meat and coleslaw or bean salad for a side, tomato salad, cold stuffed tomatoes, cold chicken that you grilled the day before, cold fried chicken (if you can afford to buy it already fried from someplace), or cold roasted chicken that you purchase from the grocery (normally pretty cheap) with salad sides.
Macaroni salad is good, too, Bug. If you put enough ham chunks in it, it could serve as an entree.
Sometimes groceries have specials, too, on stuff about to go past its "sell by" date, though everything is good for a lot longer. This is true even in the deli section of most stores. If you have a grill, you can always cook meat on the grill and if it's too hot to eat it like that, chill it for the next day.
When it's really hot, I don't have much of an appetite. But you're so tiny, you probably have to eat something or you'll feel weak. I like cold soups, too, but not everyone does. I made some celery soup a couple of weeks ago and had it hot that night and cold the next day for lunch. It was delish.
I hope your houseguest can help with your expenses, too, especially since your husband was laid off. So sorry you're having trouble right now; I hope your husband gets a job soon and I'll add you both to my prayers.