Spirit has round-trip flights from Dallas (DFW) to Baltimore (BWI) for $54, NONSTOP. Flights September to March. Departures on Tuesday, Wednesday, and Saturday. Extended weekends available. Origin/Destination reversible.
Spirit fares do not include a free carry-on bag. Only a small personal item, like a Jansport SuperBreak backpack is free. You can avoid paying for seat selection if you accept the randomly assigned seat prior to boarding.