Cruise.com via ShermansCruise offers a Carnival Cruise 4-Night Mexico Cruise for Two, with prices starting from $428. (On the ShermansCruise landing page, scroll down and click "Book Now" next to the September 10 sailing date.) That's the lowest price we could find for such a cruise by $20. This roundtrip cruise aboard the Carnival Victory departs from Miami, FL, on September 10. Book this travel deal by August 31.