I was unable to find a good C36 here in Illinois. I ended up buying it from a dealer in Newburgh, NY. Luxury Motors is a fairly new outfit, and has been expanding like crazy. I have never done business with them. I can make the following recommendations when looking for a C36:
1) Carfax, a wise investment. 3 C36's, I saw here in Illinois, were totals that were imported from other states to clean the title.
2) Find a mint C36, repairs can eat you alive. Some of the parts are rare and hard to obtain. God help you if you need an ECU. IMHO, less than pristine C36's are not discounted enough to overcome the risk.
3) If you do buy one, find a good independant shop to work on it. If you live in this area, I recommend Helmut and Vito's in Downers Grove.
4) When test driving, if anything feels odd about the suspension, run away.
5) Don't bother to get one with the integrated phone, no one will activate analog phones anymore.
6) For reference, I picked mine up for $13K with 88K miles. It has all options except the phone.
7) Check carefully for oil leaks. The original head gasket had problems, will cost about $1500 to repair if it has not already been replaced.
Best of wishes in your quest.