What's a good pay to download music site

[Black Box]

I used to use WinMX but ever since this big music industry lawsuit I am staying away from that free stuff. Trying to find a good site where I can buy popular music (hard rock and alternative), not the obscure, never-heard-of-them-before-bands. Something that allows downloads by the song or by monthly/yearly membership.

What do you all use and what do they cost?

Thanks
Steve