to the OP good luck getting a bargain, many of us here do love a good deal.
Caveat Emptor though.
Buying any car I price up consumables (brakes, tyres, next service, maybe clutch?). Unless you buy a freshly serviced car with good brakes and tyres any GranTurismo might need £2000 in the first year.
If you were selling a "cheap 4.2", would you do the above?
Good luck, you might get lucky. Running these cars on loose change may be impossible.
Add to that the market trend of rising second hand prices (including auctions) and iy might be unicorn hunting season.