You have three coil wires and three high tension leads that piggy-back to the next cylinder. So each coil wire is responsible for firing two cylinders.
The coil wires are made of solid copper and virtually never wear out. I don't remember how much they are off-hand, but I'm sure they are over $200 for a set.
The coil wire ends (or boots or connectors) are about $7 to $10 each, depending on where you buy them.
95% of all missing or misfire problems on M104 engines are due to a bad connection on these resistor boots.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".