Hi
Not sure if you were complaining about the quick resale/price differential or simply commenting about someone trying to make a profit on the car.
I have been involved with a company who buy and sell second user equipment for many years and where I can see something undervalued or have a customer in mind, I will buy from Ebay and then sell on at a decent profit elsewhere (or even resell on Ebay). There are some risks in what I do and hence the margin in the buy to sell has to reflect this, unlike new/warranted equipment.
So if the guy has bought on Ebay for £6500 and 'thinks' it is worth £10K using this route to market, then I see no problem in him doing this. As far as I can see he is taking on a fair risk with this type of car in that it has a fairly limited market and hence could easily be left holding on to it for a while. He also has sellers fees with the auction house, ie he has all the financial risk.
As to whether it is worth £10k is down to any customers he can find, given that the final Ebay figure was £6500, may mean he has a false sense of the car's value, but that is the game you play with these things.
The price may also reflect some work that had to be done or any warranty he is offering, though through the auction route I guess this will be limited.
Peter