Hops are hops. It's an herb. A "feeling lucky" search in google would even have given you useful information.
http://en.wikipedia.org/wiki/Hops
EDIT: As to where... just about any herbalist or health supplement store ought to carry hops.
http://en.wikipedia.org/wiki/Hops
EDIT: As to where... just about any herbalist or health supplement store ought to carry hops.