Well, I mostly buy music nowadays. but I’m also not as broke as I was growing up and the tooling to convert media to digital is a lot better as well. Between Ebay, Amazon, and BandCamp you can find pretty much anything on either physical or digital formats.
If you were looking to sail the seas, there are Spotify downloaders that download music from Spotify playlists/albums, sourced from YouTube, and of course, alot of music is available via torrents including some rather obscure stuff. Last time I looked on Pirate Bay (about six months ago), there was still a healthy selection of music with active seeders.
For the really old and/or obscure, try the Internet Archive. It sometimes amazes me what they have in their archives. Not all that I’ve found should be there.