Where to find Ayu/Jpop CDs in London?

Just want to say, that the Japan Center no longer sells CD's. It used to, but I went there last week and they had changed everything and expanded.

There is a small shop in the Soho china town (Picadilly) which sometimes sells Ayu CD's, very expensive though, not worth it. They were selling GUILTY CD+DVD for £22 and CAROLS CD+DVD for £20. Waaaaay over-priced.