Frontier has round-trip flights from San Antonio (SAT) to Cleveland (CLE) for $38, NONSTOP $19 each-way. Flights on Fridays in August and September. Origin/Destination reversible.
Note: Frontier fares do not include a free carry-on bag. Only a small personal item, like a Jansport City Scout backpack is free. Checked bags cost +$35 each-way. You can avoid paying for seat selection if you accept the randomly assigned seat prior to boarding.