American Airlines has round-trip flights from Dallas (DFW) to Montego Bay, Puerto Vallarta, San Jose or Liberia, Costa Rica (MBJ, PVR, SJO, LIR) for $304-$437, NONSTOP or with a connection. Flights January to May. No Saturday departures. Weekends available. Origin/Destination reversible.
LIR at $304 is the cheapest airport into Costa Rica.
SJO and PVR is about $378-$388.
MBJ at about $431-$437 is the most expensive in this group.
A Carry-on bag and also a personal item is allowed for free on American. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.
Read More Cheap Flights: Dallas to/from Montego Bay, Puerto Vallarta, San Jose, or Liberia, Costa Rica $304-$437 r/t [January-May] – American Airlines