It's not hard to find free music online if you know where to look. And if you're motivated enough to spend some time hunting you might even dig up a high quality MP3 file. If you give two shits about a WAV file or high bit rate MP3, check this website out. Soundcloud Download will let you download any file via Soundcloud regardless of whether or not the person posting the song has made the download an option. At 128 bit rate you're not going to DJ these out, but they'll definitely do the trick for your MP3 player.