Fares at this price are for the VivaLight option which includes 22 pounds of carry-on luggage only. Extra weight allowance can be purchased at booking for much less than at the airport. If you need to bring more weight, we would suggest upgrading to the VivaBasic fare for $226 roundtrip, which also includes 33 lbs. of checked luggage. This fare includes the $25 USD (approximate) non-resident fee. Price will be about $25 less for Mexican passport holders or others exempt from this fee.
Flights are available daily from the inaugural flight on October 18 through November 20 at this price point, but other dates outside of this range are only a few dollars more. The exception being flights around peak holiday travel. As an example, we were able to find seats on the very first flight departing JFK on Thursday, October 18 and returning from MEX on Tuesday, October 23, 2018.
Need a room in the Mexican capital? Here's what's available for the mentioned dates on Hotelwatchdog.