Soup is a great inexpensive way to feed your family, and unless you're Emeril or Wolfgang Puck, there are easy, cheap recipes to follow. A vegetarian soup is great because you can throw in almost any veggie you have in the house -- consider it the last stop for leftovers!
One inexpensive option is a tortilla soup which doesn't so much describe the recipe as how you serve it. Add onions, corn and diced tomatoes to a couple cans of vegetable broth; you can spice it up with carrots, beans, mushrooms, chilies, spinach, a little asparagus or whatever you have in the fridge that you don't want to waste. If the entire family doesn't want to go vegetarian, you can even do a separate pot and add chicken or use a chicken frame left over from a roast to make your chicken stock.
Serve the soup topped with grated cheese and tortilla strips and you'll have a warm, delicious meal. It's healthy and it's cheap so both your doctor and your financial adviser will thank you.