I've bought a few pins on here, the members I have dealt with have been excellent.
I definitely don't post as much as I should. I do read the forums a lot.
But the above is why I'd think long and hard before posting a pin for sale here. I see it all the time.
I think if anything is say, above 10-15% of the hypothetical "going rate," there really is no need to comment. Older machines more difficult as they may come up for sale less often, condition and mods. And even in that case your going rate might not be someone else's.
Or say +/- £500 or more for newer machines.
If someone is in the position to drop £8,100 on a new pinball machine they are probably sensible enough to decide if they want to pay £7,500 for a nearly new one.
If someone posts a Leathal Weapon 3 for sale for £7,500, by all means make your comments to protect newcomers.
The above there is no issue with and it's not fair for the seller. All it will do is discourage people to list pins for sale and the losers in that case are the people on this forum.
OP - good luck.