There's no such place, oceanfront property is too expensive to be anywhere near Mayberry. You also don't see the time and temperature displayed outside the bank in a coastal California coastal city like you would in Mayberry. San Diego isn't New York or Tokyo, but it isn't Mayberry either.
Mayberry by the sea wouldn't be in California if there was such a place. California is nothing like Mayberry. Back in the late 1930s it might have been more like Mayberry than it is now, but not today. Really though, nowhere west of Oklahoma is much like Mayberry, it's a different world.
There's no such place. If you think you are from Mayberry, you're not from Mayberry.
People from Mayberry don't know they are from Mayberry. You never sea a beach in Mayberry, which is why there's no Mayberry by the sea anywhere.