if you have bags of money try the paul stolper site : www.petersaville.com
if not, try ebay, although any original stuff will be even more expensive
ive always wanted one of the weiner 711 posters or touched by the hand of god. maybe someday when im not a student.
i got this 3rd rate hacienda axonometric and some postcards and jumbled them together on a slightly frosted piece of transparent paper over white, framed it, and , it works quite well. there is a "peter saville palate" i found, that works well when mixed in your own way, to suit your own room.
would still kill for that weiner though. someday, after college 
also, try hanging the 12 inches on the wall. technique, closer, pcl, are , in themselves, works of art.