How do I find cheap flights from Toronto, ON to Montreal, QC?

Planning to visit a friend in Montreal, and he sent me a link for a 30$ flight from Toronto Island. Had to postpone the trip, now I can't find anything close. How does he find these flights? What sites to check out?How do I find cheap flights from Toronto, ON to Montreal, QC?
Your choices are Porter Airlines from Toronto City Centre (Island) Airport and Air Canada or Westjet from Toronto Pearson Airport. All three land at Montreal's Pierre Trudeau Airport in Dorval.



The Porter Airlines offer was probably a special introductory offer when they started up service just a few months ago. Air Canada and Westjet constantly try to outgun each other with specials. Often these specials last for one day only and are only available on their websites.



You should get in the habit of checking all three airlines' websites daily for possible specials.
Best will be www.aircanada.ca to avoid any problem last minute.How do I find cheap flights from Toronto, ON to Montreal, QC?
Jazz

West Jet



http://www.westjet.com/