Well, they are an Atlantic species so California could only have this species of octopus shipped...
try any fish exporter/shop in Florida, thats the best bet. But even then it might not be 'true' joubini you get... there are several species that all look similar. O. mercatoris is often incorecctly labelled as joubini for example...
Which part of Cali are you in ? I would check with your local marine store and see if they can't get one in from Florida with their next set of eascoast fish...good luck !
And also, how come you don't want a bimac ?
It is rare to see O. joubini for sale. This species is often confused with O. mercatoris that is common in Florida and that is available this time of year. I picked up a brooding female at a store in the Bay Area last week and a couple of the hatchlings are doing quite well.
In March and April, Tampa Bay often has O. mercatoris from the Gulf.