I can see this from both sides, as a seller I want as much as I can get from an item as the proceeds usually go to fund more bike kit.
But as a buyer I’d be very annoyed if I’d just paid for something 2nd had that I could have got for just a little more brand new, usually with a warranty etc.
As mentioned above, I think that the forum should be a community where everyone is out to help each other.
IMHO If people want to over charge / rip people off then they should sell stuff on eBay or pinkbike etc.