I moved to Texas in June but I left my cello in Maryland because I thought I would be spending more time in Maryland. However, it didn't work out that way so I'm flying it back with me. I researched a couple of options, one of which was to purchase a a flight case for my Bobelock 2000 cello case with the intent of checking the cello in as luggage. Apparently there are travel cases for Bobelock cases, but they are not the same as flight cases. The only flight case I could find was for Bam cases and they cost around $700. Not sure that my Bobelock case would fit and that the return flight was less than $100, I decided to buy my cello a seat.
I usually fly Southwest between San Antonio and Baltimore (BWI) because they have a direct and they're convenient. I first booked my round trip ticket online and called reservations to book a seat for the cello. The agent was very helpful and she reserved a seat for the cello and tied that ticket to my roundtrip ticket. When buying a seat for an inanimate object, they issue the ticket in your name with an IXS suffix (Inanimate Xtra Seat, I think). It took more than one try and they issued a couple of confirmation emails but it all seemed to work - until I tried to check.
When I tried to checkin at the kiosk, I was told to see a gate agent. Apparently, Southwest's reservation system was unhappy that my return trip included a second seat under my name and it wouldn't let me checkin. Southwest solution was to break my reservations into individual legs, i.e. three one way tickets. They issued new confirmation tickets for the return flight, but the cello's ticket lacks the IXS suffix, so we shall see.