Here's my advice for cheap, versatile ingredients. For context, I'm from southeastern USA, in a large city, and this is what is available to me:
GRAIN and BEAN
-Dried beans (especially dal & chickpeas. get some masala packets for cheap and there's a lot there. chana masala is my favorite, and pani puri is GOOOOOD, my favorite snack)
-Farina
-Grits (I make mine with butter and goat boullion!)
-Bulgur wheat
-Couscous
-Tortilla
PROTEIN
-Canned fish (I'd say tuna is the most cost-effective. With canned salmon, eggs and bread crumbs, you can make salmon cakes.
Like my great-grandma used to make for me. Don't take the bones out!!! They're good! I also like the canned saury from Asian markets)
-Dried soya and the like (veggie protein in various sizes and shapes, highly underrated, makes a great pepper "beef")
-Canned chicken, luncheon loaves (may not be as cost effective as fresh meat, depending on your personal situation and how often you eat meat, if at all)
-Whole chicken. you get meat, soup, skin and fats. It's a good value if whole chickens are cheap around you. Old hens especially.
VEG and TUBERS
-Canned chopped/crushed tomatoes
-Frozen spinach and/or kale (add to everything, soups and all)
-The humble potato
-If you have access to them, Korean sweet potatoes are very sweet and delicious like a custard cake, just roast and eat. Wrap in foil and save in fridge for an anytime nutritious snack.
-Butternut squash/pumpkin/acorn squash etc. Roasted.....delicious. Also very easy to make healthy, filling, decadent soups with. Roasted onion, carrot, celery, squash, then herbs and seasonings and water or stock, blended....perfect soup.
-I think fresh green beans are worth getting vs canned. They are still usually pretty cheap, and cooked fast at a high high heat in a wok chars them a bit, cooks them, but keeps them firm and crisp. Turn heat down, add a bit of butter and oyster sauce, careful not to burn. It's one of my favorite veg dishes--and if you're on a budget, I'd say it's pretty rich and decadent for the cost.
SEASONINGS
-Dried herbs (thyme, sage, methi)
-Dried minced onion and garlic powder
-Bouillon (I'll often use flavored bouillion instead of salt in various things)
-Garlic/ginger paste
-Soy sauce
-Fish sauce (Three Crabs brand, my preference [even over the $$$ fish sauces])
-Oyster sauce (the one with the lady in the boat. It's a bit more expensive than the regular Panda brand one, but it's better and you'll have the bottle for a long time)
-And for your consideration, dried mushrooms (are a bit expensive, but are usually bought in larger bags and store for a long time sealed in the freezer)
Especially if you're eating on a budget, I suggest psyllium husk (Metamucil) supplement daily. Proper fiber intake is important for digestion, mood, and overall health. Many people, at least in the US, don't get enough fiber. It can make a huge difference for your well-being.
If anyone wants advice for cheap recipes, please reach out. This is a bit of a specialty of mine. I also learned a lot from my dear husband--wanted to give him some credit here.
With love,
Deebo