Great find,
I would like to note that deals havn't changed much. Because, Whites sends you a 5 dollar gift certificate when you perchase from them.
It looks like that address went residential. But, I did a search in the yellow pages on metal detectors in pleasant hill Ca.
Not alot to go on but found two companies with matching area codes.
Jimmy Sierra Mining
(415) 488-8131
White's Electronics of Ca
(415) 488-8133