From a previous post:

"Porter’s highest Toronto-Chicago seat price is $239 CDN or with a frequently advertised 20% discount, $191.20 CDN. An average 18% load to Chicago amounts to 13 passengers. At 13 passengers paying the highest fare with a 20% discount, $191.20, yields $2,485.60 a few dollars less than the breakeven for direct costs."

Where do you get this information? The highest fare between Toronto and Chicago is over $900. That's where all airlines make their money, on last minute bookings. Even with the 20% discount that's still over $600. I'm sure there is not a line up of people purchasing at that price, but it's the last minute business people purchasing tickets that make airlines money, and not just Porter.

Dan