Where can I get music for my IPod legally and for free for only one payment?

I usually got my music from my best friend, but I recently moved so now I have no way to get music. Sadly, mine is starting to get boring, so I would like to know if there is any sites out on the internet that provides free music with only one payment at the beginning. You know, you pay 50 bucks and you get free music for life. That type of sites.