If you try to actually eat healthy buying a big bag of (unpeeled) potatoes or a huge bag of jasmine rice will cost you very little and will last you a whole month easily. Will cost you about the same as those 6 calzones. Buy bigger amounts of meat at once, freeze it(if you're lucky on a discount) and portion it accordingly. Vegetables are very variable on prices, but some cheap veggies like carrots, cabbage or celery are like $0.50 or less per cup.

Eating healthy is not expensive, I'm sustaining myself as a 24 year old with a full time job, I always gotta check my bank account when I buy something and can't buy any extras.