Just start with rice or pasta, throw in a can or bag of vegetables, some beans, maybe a little cheese & you're done.
A 20# bag of rice is like $5.

If you've got a few square feet to spare in your place, fresh cut lettuce or spinach contains almost all the veggie nutrients you need. Get a bag of leaf-lettuce seeds, it'll be ready in a few weeks and, with normal grazing (just trim little patches down to about 1/2in from the soil as you need for meals) a small bed of it will keep growing and last months.
Fresh food is the most nutritious. By the time it gets to the store, more that half the nutrients are lost. I used to work in produce distribution, and I gotta tell you, you're way better off nutritionally, as well as financially, growing a small garden yourself.
A tiny patch will produce plenty of fresh leaf lettuce for you, and honestly, it takes next to zero effort to attain a good bit of self-sufficiency.
A pack of seeds costs what? 50 cents?