There's some genuine cheap food targeting service and construction workers - dollar pizza, rice and meat places, Chinatown - but you also get, for example, somebody who went to Berlin, saw döner kebabs, and now are charging $15 to make them here...
I'm sympathetic to the issues of cooking for 1, but I'm skeptical that it's really cheaper to eat out and get the same quality and healthfulness that you could get from cooking.
I purchase meat in Chinatown on the regular for remarkably good prices.
I guarantee that it will be cheaper to cook a meal equivalent to what you get from a food truck yourself. I live in a area whose cost of living is on par with NYC, and have never seen a grocery bill to the contrary.
> Additionally, unless you meal plan very well, some of your ingredients are going to go bad; you can’t really purchase enough celery for just one meal.
Egg salad uses abundant amounts of celery and can last several days in the fridge. Stews and soups also use lots of celery and both freeze/defrost very well.
In my experience, the hardest thing to meal plan around is fresh aromatic herbs. Hard to figure out how to use a giant bunch of fresh tarragon or mint without getting sick of it.
Additionally, unless you meal plan very well, some of your ingredients are going to go bad; you can’t really purchase enough celery for just one meal.