Where in the city where you can have a delicious, satisfying meal for under $5 including tax, preferably much less? I'll take places where they give you very large portions for more than $5, so you could make two or more meals out of it. Bonus points if it's healthy.
Let's exclude by-the-slice pizza and street cart falafel - they're too easy. But other exceptional street cart food is fine.
Here are some things I can think of to start off with:
Punjabi Grocery and Deli (east village) - a large plate of food is under $5 and could be two or three meals.
Banh Mi Saigon (chinatown) - one of their $4.50 vegetarian banh mi could probably make two meals in a pinch, or one big meal.
Kati Roll Co. (in midtown east and in the village) - some of their Indian rolls are under $5.
Roti Roll - Bombay Frankie (near Columbia) - all of their Indian rolls are under $5
The Vegetarian New Yorker: http://vegny.blogspot.com/