Potatoes are excellent, I couldn't eat them raw though. :yuck:
Walmart has incredible 2 pound subs for $4.95, it's almost all cheese and meat. They're made fresh daily, I highly recommend them.Subway/Quizno's/Chipotle. A single burrito or a footlong sub will provide all the nutrition you need for a day, and almost all the calories, at the cost of $150 to $200 a month. You will need to cut it in half, of course. Supplement with ramen noodles to 1500-2000 calories a day.
Speaking of Chipotle, in many places there are authentic Mexican hole-in-a-wall restaurants catering to day laborers & such, they will be cheaper than that.
I'm pretty fond of hamburg/bread stuffing (like a seasoned meatball) topped with tomato sauce and cheese.If you like cheese, then stuffing bell peppers with just about anything and adding shredded cheese on top is both nutritious and cheap (depending on what you stuff it with)
As far as I'm aware, yes. And with $1000 to last 6/7 months.