The consensus buying wisdom is to buy the best, already-sorted car you can find rather than a cheap project, and to accept that a well-maintained 600 can be very reliable yet remains very expensive to keep up. Owners stress the car must be driven regularly or things fail from sitting, and that a buyer needs both a full wallet and patience for slow parts hunts.
Buying advice: buy sorted, drive it, and reliable is not the same as cheap
Mercedes-Benz 600 Grand Mercedes (W100) · buying