Hi!
The flight is at 2h30 p.m. and costs 150 USD.
Check here: AERODOMCA
You have to email them and make your reservation (I always say that it?s too risky to go to the airport without a reservation, even if the flight usually is empty...)
And I?ve just found a website where you can buy your ticket online (for Aerodomca), by clicking at "Regional caribbean flights": AeroDomca - Flights to Caribbean with AeroDomca . But perhaps there?s an extra tax for the service...