It took me a second, but I think I can explain the discrepancy... there's a 1990s version of the Aero-Compax based on the ubiquitous Valjoux 7750. I think one or two of those have sold recently, and those typically go for ~$1-1.5k.
The pricey one dates to the end of the 60s to 1970s.
Click to expand...