Only thing I don't like is that it's a tiptronic and not a manual. Sports Chrono is nice to have but not essential, but it feels slightly strong money to me.
2 years ago I paid £30,000 for a mint 2007 C2S cabrio with a massive spec, way higher than that, OPC warranty, PSE, Sports Chrono, hard back seats etc etc and a manual. Prices have if anything gone up since.
It isn't a very bad deal, but it definately isn't a great one purely because its a tip, imo!
Have you driven many? Are you sure you want a C4S? Go and drive some, 2 and 4 feel very different, and personally I hate the tip box!