Cruise.com via ShermansCruise offers a Carnival Cruise 5-Night Mexico Cruise for Two with prices starting from $548. (Scroll to the bottom of landing page and click "Book Now" next to the September 15 sailing date.) That's $20 under our mention from a month ago and the lowest price we could find for such a cruise in September by $10. This roundtrip cruise aboard the Carnival Triumph departs from New Orleans, LA, on September 15. Additional fees and taxes may apply. Book this travel deal by July 31.