I also have a W111 220Sb 1961 with front disc brakes, it has been under restoration since 2005. I think you already know spare parts prices either NOS or remanufactured ones.
New pair of rear light clusters costs around 50,000 baht, a pair of stacked US headlamp assembly costs around 30,000 baht, a reissued ivory white-colored steering wheel plus padded horn ring cost around 25,000 baht!! I got my car free of charge from my close friend's sister, then spent more than 500,000 baht now, the bills and receipts are about an inch thick!! So, if you are really willing to restore this vintage model, be prepare to spend some money if you want an almost brand new Mercedes W111 fintail!!