American Airlines, Delta, and Envoy Air as American Airlines Eagle have round-trip flights from Austin or San Antonio (AUS/SAT) to Key West (EYW) for $214-$217 with a connection. Flights June, September, and October. No Thursday departures. Extended weekends available.
Carry-on bag is allowed for free. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.
Click for more details and booking links Cheap Flights: Austin or San Antonio to Key West $214-$217 r/t [Sep-Oct] – American Airlines / Delta