I downloaded LIMEWIRE basic, on my computer, which is free. I search soundtracks and nature sounds in the audio search engine and the results are plentiful. This is the cheapest way that has been working for me. I am able to download as much music as I like; oldies, gospel, jazz, instrumentals, etc. and then make my own cds.
This is just a little advice that has worked and still is working for me.