Get back to Luca when you have a chance after the Blitz Ball Tournament, or before you fight the last boss. All music that you can hear in Final Fantasy X included the music when you rest at any Inn cost 250 Gil. For the Movie, it cost about 500 Gil. You can only buy the entire movie that you already view it and the soundtrack that you already hear it. Buy the movie at the man at the left side of the cinema entrance and buy the soundtrack at the right man at the entrance too. You can also buy it after you get an airship.