there are lots of public domain grateful dead recordings, some of good quality, on archive.org
i'm sure there must be some other fantastic jam band recordings available for free with a little snooping around.
there are always lots of good free dj mixes on various edm forums where an artist will showcase their music or share what they are passionate about for free.
a lot of libraries have cd's for borrowing (this is where i first heard aphex twin's cheetah album) and there is freegal music that can be accessed to download to own a certain amount of mp3's a month, and I am pretty sure listen to via streaming through their curated list.
"
Freegal® is a free music service from your library. All you need is your library card number and possibly a PIN if your library utilizes them. Freegal offers access to about 15 million songs, including Sony Music’s catalog of legendary artists, and over 40,000 music videos. In total the collection is comprised of music from over 40,000 labels with music that originates in over 100 countries. There is no software to download, and there are no digital rights management (DRM) restrictions. Access to Freegal is limited to patrons of subscribing libraries."
There are several ad supported music streaming services, and they are trivially inexpensive.
of course there are music podcasts (i suggested nosia radio) that will explore different vistas of sound, some may be of your liking.
there's also stuff like hearts of space and I think various streaming radio stations, like legowelt and others.