It used to be really common for film scores to be released on record. In the eighties they released most of them. There were many times that I would go see a film and like the score and go straight to the record store and buy it. That being said, they do not seem to be released anymore. I would suggest going to used record stores. Most of them will have a "Soundtrack" section and, while soundtracks are not scores, they are usually mixed in there. You may not find current ones but there are many great scores from movies past. In fact, I am listening to "The Mission" by Ennio Morricone as I write.
It is really frustrating because I used to buy many scores starting in my early twenties and now I see a film and wish I could buy the score. Luckily I have many from years ago.
Good luck.
David R.