"commodity" items like bearings, bulbs, wipers, brake parts, glass, etc, always have the most apparent markups.
That is because these parts are either standardized, or sell with enough volume to create 'economies of scale' and draw competition into the supply lines.
Dealers are generally forced to use the 'factory' distribution channel, which is protected from normal market forces. Even if the OEMs are producing the exact same part without stars on them for 1/3 the price...
1986 300E 5-Speed 240k mi.