Southwest has round-trip flights from Austin (AUS) to San Jose, Costa Rica (SJO) starting at $290, with a connection. $126/$164 each-way. Flights August to October. Weekends available. Origin/Destination reversible.
Note: Don’t waste your time with Spirit “deals” on this route. They don’t allow for free bags, charge for seat selection, have almost no weekend availability, and have really bad connection times.
Note: You can save up to an additional $200 if you book your Flight+Hotel together as a package on Southwest Vacations and use the ‘INTL200’ coupon-code at checkout.