In the 2000s I remember the OS releases being $130, which (depending on exactly what year you start from) is equivalent to $200-250ish today.
Not a yearly cadence because back then they only released a new OS version when it was done and had features worth releasing, but even every two years that wasn't a cheap update.
i think it was only a few years that lasted, but not positive. There was a brief period where you could actually license MacOS to run on non-Apple hardware, I bet they charged for that too.