As an interesting post script to this, I received an e-mail from SFBC that their sale was extended until tomorrow so I decided to order a few more of these. I put these in my 'Cart' and they rang up at $9.99 each again. I went back to the main web-site to browse for more books, added some more and then went to check out. When my order was being summarized, the price changed from $9.99 each back to $49.99 each. I tried removing them from my cart and then adding them again, but they kept coming back as $49.99 each. I called their Customer Service line and talked to someone and they said that any book that is regularly priced at $39.99 or more does not qualify for the $9.99 sale. So, it looks like I was lucky a few weeks ago and caught a glitch in their system when I got this for $9.99!