Every student in New York City you talk to will know about Mamoun's. The reason? Falafel for $2.50. A gigantic platter for $5.
The prices for other sandwiches are more average (my chicken schwarma, below, was $5). I am never unsatisfied here, but never wow-ed. The chicken is a little dry and not seasoned thoroughly, so the lamb is a better option. The falafels are worth every penny of $2.50, but probably not much more. The vegetables obviously come from cans and bags.
The Greenwich Village location was established in 1971, and is always crawling with people especially at night. It's a little less of a pain at their "new" East Village location, but either way plan on eating your sandwich on your feet unless you are willing to wait a bit and dive for a free table.