I paid $72 for my cord. Different engine, but I can't expect that the cord is more expensive for your engine.
I have seen cords online for about half of what I gave the dealer, but they did not have the brass nut to hold the cord onto the heater, and they were not fully wrapped with insulation. They were clearly worth much less than half as much.
The block heater on my older W124 had rounded banana-style prongs. I was able to fit a plug from electric blanket to it. The plug had the same size of prongs, but different distance between them. I spit the plug in the center without cutting the wires and was able to adjust the distance to Mercedes prongs.
well the mechanic found the cord, it was working on the tester, but when you turned the cord it shorted, so they changed the cord prong, sealed it with silicone, and whammo fixed, 18 bucks, taxes in, i know i could of done it myself, for like , 5 bucks, but it was -36 celcius, thats -34 farenheight and let them do it. thanks all