I have seen a number of postings lately by people who have recently aquired their first 60s/70s Mercedes sedan and want to "restore" them. This thread is for them.
Even assuming that the cosmetics of such a sedan are very good, the cost of returning the mechanicals to something near original performance generally ranges form "high" to "very high". Unless the car has previously been owned and maintained by an astute and dedicated owner, there will surely be many rubber parts that have "perished" over time and should be replaced. More still with the early 70's EFI motors.This has as much to do with basic function and reliability as it does with the overall performance of the car. And then there are the "hard" parts...
Lack of basic maintenance (and there was a lot more that need attention in those days), is common among these cars as they passed from original well-to-do owners down the economic chain to negligence and indifference. As long as it ran that was good enough. Compounding this problem was the retreat from dealership maintenance to local garages where a thorough knowledge of the various models was unlikely. And over time even the Mercedes dealerships lost the mechanics who were expert in these models to retirements and the like. Hence Mercedes' recently employed "certified classic mechanic" program at selected dealerships.
Almost any truly competent mechanic for these cars will cost around $100/hour. Even from discount houses, parts are expensive, and more and more of them are being discontinued.
Even really good examples of these cars--meaning excellent cosmetic, low mileage and no known malfuntioning systems are rarely worth more than $15,000. Most of them sell for far less. The highest price I have seen on ebay was a very low mileage California 300SEL 4.5 that went for $22,500. An equivanelt condition same model with the legendary 6.3 motor might fetch $40,000. In all probability the low average selling price of these cars is a reflection of the fact that knowledgable afictionados of these cars already know that the purchase price is only the beginning.
I have said all this in the hope of saving some of you from a hearbreaking financial experience with one of these cars. But as my list of past/present cars indicates, I love these cars. When they are right, they are a delight. The build and materials quality were second to none in their day. And their engineering was in a class by itself. Just be aware, is all I'm saying.

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Berfinroy in CT
Present vehicles:
1973 300 SEL 4.5
1959 Rolls Royce Silver Cloud I
1973 Citroen DS23 EI five speed
Past vehicles;
1959 Thunderbird convertible/430
1958 Bentley S 1
1976 ex-Max Hoffman 6.9
1970 300SEL 2.8
1958 Jaguar MK IX
1961 Jaguar MK IX
1963 Jaguar E-type factory special roadster
1948 Plymouth woody
1955 Morgan plus 4
1966 Shelby GT350H Mustang