While looking for Mexicana fares between MTY and CUN, I found that it is cheaper to fly with a stop in Miami than to stay inside Mexico.
A MTY-MEX-MIA-CUN-MIA-MEX-MTY ticket with Mexicana costs USD 550 and a MTY-MEX-CUN-MEX-MTY ticket with MX costs USD 553! I can't believe it! I seriously can't. I hope the new LCCs help bring down these outrageous prices. I think it can even get cheaper if you fly Aviacsa MTY-MIA and then MX/AA MIA-CUN.
Saludos desde Caracas,