I just got to college in 2000 and had highspeed Napster. From there I found some sketch Russian site I could get music from for a few years in the early 2000s but there was also a huge used CD store in my college town with reasonable prices I used to frequent. Now days if I want to find a bunch of new music I dont know, Usenet for the win. But honestly most of the stuff I like is on bandcamp usually and I will go buy the bands I find on use net. My best discovery has been Brant Bjork (he played drums in Kyuss but makes chill ass rock) and PallBearer and Arkansas doom band that is pretty great. I have since purchased their catalogue on Vinyl, mostly on band camp because it is hard to find in stores.