As has been previously said, all retro pricing is subjective - the majority cannot be quantified or qualified other than against the limits of our own wallets (and credit facilities!). Would we really pay the monies that we pay for bits of 10-20 year old metal if it were any other way?
I'm not quite sure I see the difference between "I'm interested but the price seems a bit high" or "The price seems a bit high, how about £xxx", but at the end of the day it's John's site and he puts a lot of effort into it so his rules are his rules. I'm free to go elsewhere if I feel John is being unreasonable, which I don't.
So someone, buy the bike for the quality components (and probably worth the money) .... and give me first refusal on the frame