I received some family videos from the 1960s thru the 1970s, presumably all originally from Super 8. I was surprised to see that some of them from the mid 70s had sound (and a cursory glance around the net indicates that seems to be when they started becoming available to the public).
What’s not easy to find is how much these cameras cost in the mid 1970s. To compare, most people I know have some kind of video camera nowadays. Back then, I knew only a couple of people who had movie cameras–and no one had sound.
1976–Super 8 movie camera with sound, $239.
1975–Kodak #130 with sound $139.
Kodak #140 with sound, fully auto, zoom lens $229.
Sankyo XL #405 sound indoors, without lights plus zoom lens $299.