There are two Disney shops where you can buy AP's at the airport.
Disney's Flights Fantastic is in the Airside terminal B, right in the middle of where Gates 60-99 converge before you get the shuttle to the main terminal.
The Magic of Disney is in the main terminal on the A side where the shuttles from Gates 1-59 let you off.
According to the OIA website, Magic of Disney is open 6:00 am - 11 pm and Flights Fantastic is open 7:00 am - 11:00 pm.
You could always call to verify hours:
407-825-2373 for Magic of Disney
407-825-6917 for Flights Fantastic