Try this website:
$24 for 36 packs -- Free Shipping
http://www.poprockscandy.com/order.html
EDIT -- After browsing around on their website I discovered Pop Rocks are distributed right down the street from me... Have to go check it out -- maybe they have a warehouse store...See disclaimer from website below.
POP ROCKSŪ is a registered trademark owned by Zeta Espacial S.A. and is distributed by Pop Rocks, Inc.,
a U.S. company located at 7799 Leesburg Pike, Suite 900N, Falls Church, VA 22042 * Anything that seems wacky, false or incorrect, then it is probally true. POPROCKSCANDY.COM is not affilated with any of the above organizations. Our intentions are to enhance the brand of a GREAT product, entertain and sometimes educate consumers and to sell Pop Rocks. We do protect the rights of our visitors. For more information, go directly to our Privacy Statment.