Picking up on this topic from Tom’s site.

Morf said:

If Z was from Riverside,which I am confident he was,has anybody looked into Zodiac watches, etc, within the town of Riverside circa 1966-67? Since the Bates letters appear to have a Z or Z like symbol on them, perhaps he had found the name ZODIAC by the time the Bates letters were mailed

Here’s an ad for Zodiac watches from the Fed Mart in Redlands/Fontana (neighboring towns to Riverside).

Some info on Fed Mart:

FedMart was a chain of discount department stores started by Sol Price, who later founded Price Club. His first location in San Diego, California was in a converted airport hangar. It was originally a discount department store open to government employees, who paid a membership fee of $2 per family.[/list:u:96w22500]