I think „fair“ means something else to everyone- plus, even got vintage bags, you do not have a ton of data points for any given combo. „Fair“ for me is what you‘re willing to pay without feeling scammed i.e. a combo of „market price“ observations in a market with imperfect information and personal willingness to pay based upon personal preferences, spending power, patience etc. and this is quite different across people, in my experience. So, you try to derive a monetary value based upon two rather volatile variables across people.
I for one do not feel comfortable to give you a „fair“ price estimate even for combos that I look at quite frequently in the vintage market. Eg I would pay a premium for not having double d rings in a Kelly - others the other way round. I love a K from the 90s and would pay more for those on average that for a mid 2000 K. So, i don’t feel comfortable to give a „fair“ price estimate because it is heavily biased by my preferences and (limited) research.
I would not want someone to pass upon their dream bag, because I tell them that the price is not „fair“ (for me). This would be such a pity for me!
Plus, basically it is a lot of time that people spend to research the vintage market - you would not expect anyone to spill out all their hard-won knowledge to someone basically not willing to put at least some efforts in themselves? This is knowledge that you can obtain by putting a bit of effort in, it is information freely available by following various vintage platforms.
Probably a topic for the unpopular opinion thread.