Usenet providers are like you internet provide. You're not paying for what's there, you're paying for access.
You have your choice of providers for this service, and they are not all created equal (just like internet providers). The absolute best is Giganews, it's also the pricest. There are referral links in the newsgroups section of this forum (stickies at the top), if you use them to make you purchase this site gets a few cents kicked it's way.
You may want to do some reading in the newsgroups section for the latest news. I am guessing that you already found this site's NZB index. There is also a good tuturial there on how to use Usenet.
