We all hit times when things are looking a tad sparse in the food department. That's not so bad -- for one thing, it means that you're cycling through your food supplies without wasting much. For another, it gives you a fresh place to start from.
First, figure out what you've got. Check the frig -- freezer -- shelves.
Second, tidy up. This is a perfect chance to wipe down shelves and scrub out the veggie crisper. Your kitchen will look and smell better for it. (While you're at it, scrub the floor, too. Makes you feel very efficient.)
Now you're ready. Begin with the basics. Eggs, butter, milk and flour can make pancakes and bread. Biscuits are not difficult, either. Olive oil is healthier than many other types, and can be used in a variety of ways. Popcorn (great for snacks), oatmeal, dry beans (pintos are cheapest around here) and rice keep a long time -- buy them in as large a package as you can afford. (Noodles are good, but can be made by hand. Buy macaroni or pasta instead, if your money is tight.) Add brown and white sugar, baking powder/soda and salt, and you've got a solid start.
Coffee and tea are nice to have around, as well -- but if need be, you can wait on those. Grinding your own coffee beans gives a fresher taste, and using a 'British-style' tea (we Americans are such wimps in this department) gives you a stronger cup.
Next, add as few or many spices as you can afford. Dried onion and garlic flavor any dish nicely. I also rely on cinnamon, nutmeg, marjoram, basil, oregano (look for a good Italian blend, if you prefer), curry and chili powder, mustard. A bottle of hot sauce is a must; add bottles of ketchup, barbecue sauce, steak or Worcestershire sauce when you can, as well as a jar of onion soup mix. (Dole the latter out sparingly to zip up homemade soup, or add a tablespoonful to your meatloaf.)
Now look at what fresh vegetables you can afford. Root veggies, like onions, carrots and potatoes, are a standard, and generally cheaper than the others. (Tip: buy a bunch of green onions, if the larger ones are expensive -- they'll flavor your food nicely, and add color.) A bunch of spinach not only will serve for salads, but is good chopped into soup, stews or casseroles. For fruit -- what's on sale? If nothing looks appealing (or cheap enough), bananas are usually the next option. (Don't forget canned peaches, pears, oranges, either.)
And finally on the list: a loaf of bread, corn and flour tortillas. Crackers, if you can. A few extra cans of vegetables, corned beef hash, soups, etc. will fill out your cupboard and give you quick meals at short notice.
The ten things I think should always be in a pantry? I'd add these, too.
This basic pantry can help you head in all sorts of culinary directions, at surprisingly little cost.