Call the airlines
The mostly uniform stateside charge is 80$ boxed or bagged each way, I called all flying from Florida to SF, CA...... same thing. The specialized carrying cases being a separate issue make sure BEFORE u buy one what the charge will be
It may be more practical to rent a bike locally in the city to which you are traveling, it certainly eliminates some of the inconvenience of boxing,getting to and from an airport, and even the extra charge carriers such as Super Shuttle charge to transport a boxed bike, 10$ extra from Ft Lauderdale to Miami in my case