thanks to everyone who gave suggestions about where to find lonely planet guidebooks here in cairo! after working my way through the various suggestions, i've posted what is evidently the best LP guidebook source, in case anyone else ends up in the same situation:
The American University in Cairo Main Bookstore. This sounds like the best option (and fodor's likes them too!), although I ran out of time to visit them. I've heard they have a full supply of Lonely Planet guidebooks.
i did not have good success at Cairo used bookstores. While most bookstores in Cairo only sell guidebooks on Egypt, i did find one bookstore that sold Lonely Planet guidebooks on other countries. however, their 3x markup over the USD cover price for guidebooks that were usually one edition out of date was, in my opinion, beyond any shade of reasonableness. i recommend you send your business to the bookstore listed above instead!
