Try this link for more info on SACD. On page 7 of this document, they list SACD purchasing sites online.

http://www.airshowmastering.com/sacd.html

The Stones SACDs are a great introduction to SACD. Hybrid layer discs that can be played as either a regular (Redbook) CD or as a SACD. It gives the user a chance to hear the difference if their system is set-up correctly.
Interesting Side Note: In a recent issue of Mix Magazine (a high-end recording publication), they interviewed the producer of the Stone's remasters. He said that as they were doing the transfer from the original masters; the path to the new analog master sounded good, the path to the new 16/44.1 master sounded better, and the path to the DSD/SACD master wasn't any different sounding than the original master!! He had a switcher to switch to any of the formats and he thought that the SACD button on it was broken because he didn't hear a difference. Pretty interesting stuff.