I've been looking for a bodykit for the CK for quite some time but without luck.
None or very few patrts of the kits for w203 sedan- or touringmodels would work on the coupe since the fit between for example bonnet/headlights and the front bumper is very different, the CK looks more like CLK(W209), same goes with the rear bumper, CK rearlights have a rounded edge against the rear bumper like the CLK, sedan- and touring versions have a straight edge. However, the sideskirts from a CLK would probably work since the distance between front/rear axel is the exact same on the CK & CLK (2.715mm), and bodykits for CLKs aren't too hard to find.
Problem is there is a lot more overhang in both rear and front on the CLK so front- and rearskirts would have to be modified to work on the CK.
I havn't found any data on the overhang on W203 sedans or touring versions, the front may be the same as on the CK but the rear is definetley a lot more.
I imagine my own CK with a bodykit like the CLK DTM or BlackSeries... mmm sweet