Good morning,
I can't believe a bike like that won't sell at that price, it shows how depressed the market is............
I am not sure, how long has there been a market for a used bike at £2K-£3K plus?
Although £15K bikes are now almost mainstream we seem to have gone from where £5K was pretty much the max unless you really went looking to this price in a very short time.
It doesn't follow that this means the market for £2K-£3K used bikes has grown. For most people this is a huge amount to spend on a bike, let alone a used one that presumably either comes with no warranty or maybe a bit of the original one depending upon the brand.

Which will of course exclude normal wear and tear and
I've spent all that money and it is still a used bike.
I have just bought a Carretta Vanquish as a new pub bike, I don't care about the warranty on that as it was £200, pretty much unused.
Added to which it has expensive wheels and a power meter, also expensive when new, this narrows down the buyer pool even further, I get that the OP is offering options without them.
A few years back I bought a couple of years old but virtually unridden CF/Ultegra Di2 bike with very basic wheels for about £800-£900, I've forgotten the exact amount, from a retailler, which sold new for £2.5K
My LBS has this
and they know pretty much all the local people who would be interested and
could afford it, but it is not flying out the door.
I have one of the 40th aniversary Raleigh 753 frames, and I noticed that a virtually unused one sold for around £350, they started out new at £1,500. Despite all the Steel Is Real hype when it comes to spending money the customers just aren't there.
Added to this there are still some staggering bargain out there if you are not committed to a specific brand and are happy with last years model.
Bye
Ian