American Airlines has round-trip flights from San Antonio and Austin (SAT/AUS) to Curaçao (CUR) for $421 with a connection. Flights in March and April.
Note: Other dates in March may also be available but they will require an overnight stay in Miami on the return flight.
Note: Carry-on bag is allowed for free on American Airlines. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.