There's a place where you pay 6.85 for western style buffet (brunch), however, I don't remember the name of the resturaunt. Anyway, don't try Chinese buffet here if you are Chinese, you won't like it. Better off try some noodles, fried rice instead.
goto montreal public website: http://english.montrealplus.ca/
click on 'bars and resturants', you will find the different styles of resturants there. as for buffet, you can search 'buffet' or 'vichy' or 'stanza' or 'new port'. I gave you the order i prefer. You can find their address, telephone, map. good luck