Musopen is a group that's been trying to release classical music that's long been out of copyright back into the public domain. How did it leave the public domain? Each recording is considered a new work, so just because the copyright has expired on the sheet music doesn't help all us lovers of Free Culture. The recordings are still copyrighted themselves. They're using Kickstarter to get money to hire professional orchestras to record classical music for the public domain. They've done this before, and they say that based on their price quotes "every $1000 buys a complete set of Mozart violin sonatas, or all of Chopin's mazurkas, ballades, or nocturnes."
If you want to support the public domain, or just plain if you're into classical music, why not give them some dough? This is a last-minute call. It closes in a few hours.