Well, this may not exactly be a deal, but Doublejump Books is offering a promotion where every pre-ordered copy of the OD guide will be autographed by the author. $19.99 (cheapest shipping is priority mail and brings the total to about $26.10) and will be available June 16th.
http://djbooks.easystorecreator.com...-official-strategy-guide-pre-order-detail.htm
http://djbooks.easystorecreator.com...-official-strategy-guide-pre-order-detail.htm