Ocean Treasures in SF has them, they are a BAR sponsor, a new shop really worth checking out (ask for a tour of the basement!), and they went above and beyond in helping me out with finding and holding those onyx clowns. It's super easy to get to too. they are right off the 101 ramp as it enters the city. Again, really great guys with an amazing setup. When I was in last week he pulled one off the shelf to show me, but I think it's a little too much flow for my 24!
Cheers,
Josh