I second Soulseek, like another person mentioned. It's one of those Limewire types of peer to peer sharing programs. You share what you've got in your music folder and others do the same. It's been a while since I've used it, but I hear it's still doing well. It's been around for ages!

Your best option will always be private torrent sites in my opinion. Usenet is cumbersome and requires usually at least two paid subscriptions. One for the Usenet server and one for the indexer you use to find your warez on Usenet. Soulseek, edonkey et al will get you music but tags and quality will be all over the place.

Troll around on tracker threads either here but most likely on reddit for open invites. Use an open invite to talk on the forums on that site and they usually have invite threads on there. Go from a open sign up to a closed private site with a little patience and a little time.