Montreal has plenty of cheap lebanese fast take out places but Boustan is definitely the best! It's cheap, the service is great, it's open late, they deliver, and the food is delicious! Not much atmosphere to sit and eat in there, but the quality of the food more than makes up for it and you can always get it delivered or take it out.
I have only ever had the shish taouk (or chicken shawarma) but their other options look equally good. I recommend getting it spicy! Their hot sauce is great!
It is well deserving of the great reviews.