United has round-trip flights from Austin or San Antonio (AUS, SAT) to Los Angeles (LAX) for $131-$137, NONSTOP. Flights October to January. Weekends available. Origin/Destination reversible.
United’s “Basic Economy” fares do not allow for a free carry-on bag. Only a personal item (like a small laptop bag) is free. Seats are randomly assigned for free prior to boarding.
The personal item size on United is smaller (9 x 10 x 17 inches) than Frontier or Spirit (8 x 13 x 18 inches).