Yes, there is probably a demand for this music, especially if it is in good condition. Your best bet would be to take it to a music school such as Julliard or Eastman School of Music, or the library associated with that school. They could tell you what it might be worth, might even want to buy it from you. Depends on where you live, but make sure that you take it to a well known, college type of music school. Or even to a college or university library.