I have no idea about your first question.
For the second, I've never seen one source that has consistently cheap prices on SACDs across the board. If such a place exists, they're staying carefully hidden. The best I can do is watch for sales and clearances at places like Music Direct, Acoustic Sounds and Elusive Disc, and if you're into classical in particular, you can often get great deals on sales discs at Archiv Music and Presto Music.