Theatrhythm Final Fantasy's downloadable songs will eventually cost ¥150 a pop. Initially, however, Square Enix is offering a 30% discount, to ¥100 each.
Originally, the discount period was scheduled to run through March 7. Today, Square Enix announced that it will be extending the period to April 18.
Eight songs are currently available for download. You can hear some samples here.
Additional download songs will be released every two or three weeks. The discount pricing applies just to current songs.