Why buy em? Just catch some, they're all over the Bay Area. I caught a bunch in Half Moon Bay. The crab traps only cost a few bucks and you can attach em to your fishing pole, and just use a chicken leg as bait.
buy yourself a crab net, and hit the Pacifica pier... or go under the golden gate bridge - for store worthy dungenous!!! Its a cheap fucken date, and they will think "wow he is so manly, he's not afraid to touch that over sized ocean insect.