American Airlines has round-trip flights from Houston (IAH) to Ontario, California (ONT) for $105 with a connection. Flights April, May, August, September, October, November, December, and January. Mostly Tuesday, Wednesday, and Saturday. No Friday departures. Origin/Destination reversible.
Note: Ontario is a good alternative airport if you’re wanting to get to Los Angeles; 40-minutes by car, or an hour by Metrolink.
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.