Well I just paid $36+shipping $USD for a campy dérailleur hanger. Was it worth it? Absolutely not for a crummy piece of metal.
Is it worth being able to finally ride my bike with my Nuovo Record Rd instead of waiting weeks/months for the next one to pop up? Absolutely.
This, folks, is the crux of the problem, issue, situation, when it comes to vintage bicycle or vintage bicycle parts value - call it what you like.
Some of us, including me, just might be willing to pay a lot for that last or special piece. For me, I have resisted paying $220.00 US plus shipping, plus import costs for an Ebay listed NOS C-Record seat post for my newly (actually last summer but too busy to get it out for rides) Waterford. But I just might spend the money - after all, the seat post has been listed since last Fall.