Does anyone know where I can download J-rock/J-pop music?

I was just wondering if anyone knew of a good site that I could download some songs. It has to be a legit site, I am willing to pay for the songs if it comes down to it. I know of Gendou.com, but that's mainly for anime songs, I would like a site that I could download songs outside of anime from groups like Phantasmagoria, Janne de Arc, Gazette, and so on. Thanks a bunch, ^_^!