Personally, it is eBay, so I would enter what I would max willing to pay, cross my fingers and I see what happens. True, that is how I always do it. Of course I would not unveil my interest not to mention my max on public forums.
On your 400 estimate: It is certainly less than it was new and you can't have a similar quality frame built for that money today. Good luck. Very bad time for selling frames, so you could very well be lucky.
Personally, it is eBay, so I would enter what I would max willing to pay, cross my fingers and I see what happens. True, that is how I always do it. Of course I would not unveil my interest not to mention my max on public forums.
On your 400 estimate: It is certainly less than it was new and you can't have a similar quality frame built for that money today. Good luck. Very bad time for selling frames, so you could very well be lucky.