I would pay no more than £1K for an S8 which doesn't drive (half that for an A8). I paid that for my Murple because I knew it was recoverable, and also for my FEs for the red leather. In the case of Sergey's, it was priced far too high to be of interest to Prestige but was still worth saving for all the rare parts.
In any other case I'll try and arrange for Prestige to acquire it and to give me first refusal on the bits I want because then they can get some value from the rest of the car and we can keep supporting each other