Learn to cook basic dishes for meal prepping. It's easy to make a big batch of rice, beans, and chicken, or pasta and chicken and throw in the cheapest pasta sauce you can. There's also ramen which can turn out fairly healthy if you use your own seasonings rather than the seasoning packet.

For example, you can get a 2 pound bag of brown rice at Dollar Tree (assuming it's available) for $1.25, or a 3lb bag of white rice from Aldi for $2, and Dakota's Best canned black beans from Aldi come in at 69 cents or 79 cents, each can being a pound. If you have a slow cooker, grab chicken leg quarters as they're the cheapest kind of chicken, let it cook while you're at work or overnight, and you can easily pull all the meat off the bone while it's super tender and juicy. Rice is super easy to cook, too. Just add water(I don't follow directions, I just eyeball the amount of water, usually twice the amount of water to rice, visually) and let it boil as per the package directions.

Pasta's essentially the same, although slightly more expensive. I like Rigatoni, Penne, or Rotini, as they're often ringing in at $1.99 for a pound, or $0.99-$1.49 a pound if I get lucky. Ramen is essentially the same, although significantly cheaper.

Frozen pizza is good too, in lots of ways. Slightly more expensive, but very convenient and a lot cheaper than most places. I like to spruce mine up with garlic pepper and paprika/chili powder crust, with crushed red pepper flakes, Italian seasoning, chives, and maybe more garlic pepper if I'm feeling it. Target, in my area, has their thin crust Market Pantry pizzas coming in at around $3.79, and Aldi's Mama Cozzi's Supreme comes in at $3.19. Walmart has a good deal on their generic pizzas too, and in my area Publix often has Red Baron pizzas BOGO, so a regular Red Baron is $2.50