York made their own horns. They were based in Grand Rapids, MI. They are similar to the Buescher True Tone, but the True Tones were much better. I wouldn't spend more than a couple hundred dollars even if the horn is in good playing condition.
Like Sax Mom said, the C melody is a fun horn to jam along with a piano or organ, or even a guitar, but there is no band music for C Melody. They were designed more for organ and piano accompanyment and playing in church than for brass band. It sounds like you got it for a decent price though. C Melodies are becoming more popular as collector's horns these days.
If you're looking for a nice vintage alto that your son can play through high school and college, I would suggest a Conn 6M.