Montreal (YUL) to Cancun: $400, Fall and Winter
Flying to Florida, Cuba and even Puerto Rico is cheaper, but they don't have pyramids.
Montreal (YUL) to Cancun (CUN): $400, return, all taxes included. (At time of writing, only US Airways via Phili). That's cheaper than from Toronto or New York!
Hotels can be quite expensive in Cancun. Consider downtown if your budget is tight (or a shorter trip). There are only half a dozen beach access points, which is seriously annoying, but OK if you know where they are (the bus is frequent, 24 hours, and cheap). Once you are adjacent to the water, the entire beach is public.
Tip: Cancun and Isla Mujeres are on Google Streetview.
Montreal (YUL) to Cancun (CUN): $400, return, all taxes included. (At time of writing, only US Airways via Phili). That's cheaper than from Toronto or New York!
Hotels can be quite expensive in Cancun. Consider downtown if your budget is tight (or a shorter trip). There are only half a dozen beach access points, which is seriously annoying, but OK if you know where they are (the bus is frequent, 24 hours, and cheap). Once you are adjacent to the water, the entire beach is public.
Tip: Cancun and Isla Mujeres are on Google Streetview.