Incredibly nice car, and I doubt you'll regret the purchase; I haven't.
In regard to 19" wheels, if you're looking at the black (with polished lip) option which were part of the Ed 125 package, may I suggest a set of replica wheels instead?
Shock! I know however, all of my genuine AMG wheels had cracked and I had (luckily) a full set replaced, courtesy of the sales department at my local dealer.. They seem quite 'soft', or perhaps it's a case of a tiny tyre and an unsympathetic previous owner but either way, there's potential to chuck away £2500.
CM Wheels I know sell a replica version of these wheels, which will likely be heavier however, they're £500 for a set with the correct offset for a C63 also.
If I didn't have the Ed 125 car, I'd probably have saved for something from HRE, ADV 1 or Vorsteiner. Vossen make some nice ones also which are a little cheaper but, my personal favourites at the moment are the OZ Super Turismo and Superleggera, which despite having a more "track" style, seem to work really well.