I would imagine that partsshop could get you Beru wires.
As to plugs, MB specifically recommends not to use Platinum plugs. I say that because it probably means more than my own recommendation (from experience): Don't use plats. There is absolutely no reason to spend extra money on plugs unless you are trying to cover up defficiencies elsewhere. (over rich mixtures, burning oil, etc.)
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician