I would buy only Mercedes original wires, whether you buy them from Fastlane or the dealer.
Original wires are made of solid copper and are expensive. This is why they rarely need replacement.
Aftermarket wires, even Bosch, are a silicone / copper blend, which is why they are much cheaper.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".