Astraweb used to be a good provider, then they started becoming far too compliant with DMCA requests to remove content. I think it's become automated. Basically, some of the most popular stuff that's posted gets taken down minutes later. I used to be with them, back when things were good for everyone on newsgroups.
I now use Blocknews for fills, and Shaw's highwind news server as a primary.
Nzbmatrix isn't such a great indexer. They don't allow certain shit to be indexed, because they themselves I believe are complying to DMCA requests. I use a combination of Nzbmatrix, Nzbs.org, and Newzbin.
Newsgroups peaked I'd say maybe a little less than a year ago. Prices were cheap, content was rarely removed, retention was high. It seems to be going downhill now, with people having to use a number of backup providers to get their content.
I tell everyone who's new to newsgroups to read this:
Slyck.com • Information . It's long, but it's all relevant. If you don't want to be a noob, read it. Jumping right into using Sickbeard, couchpotato, and sabnzbd right away won't give you the whole picture.