Hard to find a good, inexpensive lunch in this neighborhood. I've been relying on the empanada man on 53rd btw. Park and Lex for good soup and empanadas, but the other day wanted something else.
Tried the big white van on the north side of 51st between Park and Lex. Their menu advertises both slices and whole pies of thin-crust pizzas, and wraps w/chicken parm, meatball parm, sausage and peppers, and maybe one other. They also have pasta specials. The wraps are $5, the pasta seems to be in the $6 range.
I've tried the chicken parm and meatball parm, and they were both very good. It's not a traditional wrap (flatbread with fillings)--I think it's the pizza dough baked with the filling inside, so the crust stays sort of crisp and the inside is nice and hot. (this is probably not the best description, but it's like one of those Hot Pockets, or like any meat-in-dough kind of thing)
FWIW, the people ahead of me were picking up pizza and raved about it. Also, the guys running the truck were very nice, which always helps.