A half billion per launch is actually a bit high, in the dollars of the time, it was a bit north of $400 million per launch. NASA estimated that shuttle launches were going to run under $10 million per launch, so, they were off by a factor of about 40.
Good point - The tremendous “multipliar” of what the actual cost per launch was, compared to what we told to expect to pay; and how rapidly the turnaround times were “supposed to be” is probably what I remember.