£13k and mostly common as mud MDF used. I keep my new Technics SL-1210GR that I got a slight lower price cos it was a demo model in the showroom. £13k for MDF when MDF is commonly £8 pounds for 4x8.
10k was for the arm and the cartridge, I’d imagine the motor unit was around 2k. I know the plinth maker and he’s only charging for his time and materials. Like you I don’t think this customer chose a route with a good cost to performance ratio