Pauly,
I am new to this forum but have just bought clk roof bars from MB. They are £167 alusytle. The number B66850265.
However before you buy anything (new or secohnd hand) check what size locating nuts you have in your roof. My clk is an early one i think (sep2002-i have only had the car 3 weeks) and has M6 nuts. The roof bars come with M7(10.9) bolts, therefore they wont fit unless you change the bolts to M6 or drill and tap out to M7.
I suspect if you fit M6 bolts you will have to down rate the load capacity but then if you open up to M7 you reduce the nut wall thickness.
I am trying to steer away from fitting M6 bolts at the moment but if i fit 12.9 grade i should be ok. I have left it with MB (Sytner Newcastle) to sort out as i payed good money for them. Essentially i wnat them to tell me if i can fit M6
This can not be the first time this has happened so how they cant find the information is beyond me.
Anyhoo, i hope you have M7 nuts and they will flyon.
Cheers