Nathan David. Apollo/Nureyev 1978

Paintings and sculptures are very difficult to appraise online. It's best to take this to a fine art gallery/museum in your city to see if they can point you in the right direction.

I did find a little information about when Rudolph Nureyev danced Igor Stravinski's "Apollo", choreography by George Balanchine:

https://nureyev.org/rudolf-nureyev-famous-roles-ballets-index/apollon-g…

And a little about the sculptor, Nathan David:

https://artuk.org/discover/artists/david-nathan-19302017

This piece could be something that is very desirable in larger cities where the collectors of ballet memorabilia are or go to acquire, i.e. New York, Chicago, Los Angeles, San Francisco, London, Paris, etc.

Interesting piece. Please let me know what you are able to find out!