Unfortunately, unless the machine is an antique that is older than 25 years, this is illegal in the state of California. Slot machines are outlawed in the state unless they are on tribal grounds, being transported through the state, or are antiques not being operated for gambling purposes.
Despite the popularity of slot machines, California's law for land-based casinos is quite strict. Except for Indian Casinos, which were mentioned above, owning a slot machine is entirely illegal, even if it is for entertainment purposes only.