Sorry for the short notice on this one, but I just noticed this buried in the text of a routine e-mail from O'Reilly.

They're running a 50% off deal, that "expires Feb. 28, 2013 at 11:59pm PT", on selected PHP e-books...

http://shop.oreilly.com/category/deals/php-owo.do?code=WKPHP&imm_mid=0a1...

The discount code you need is on the web page above.