The market for Aeros is evolving into one for "collectable", low milage, almost Concourse condition and sky high prices. The AeroMax at Williams is an example, build 97, 3500 miles, £250,000 and it looks almost as new.
The other market is cars that are used, such as Tarka. A daily drive since 2014, 46,000 mile and not concourse, but clean and cared for with a full service history. At best £55,000: the miles run hack into the perceived value.
Insured value is not market value: to buy a replacement S4 Roadster from a dealer would cost me close to £70,000, if I could find one.