Well I sold the car privately a few months ago for 14K without the Renntech airbox, the car was on nearly 50K miles and just had a A service with MB and brand new MB battery.
Everything on the car is new, before I sold it, I replaced all 4 arms on the car, that was about £700 with Olly.
When I bought the car it was on 34K miles with 1year MB warrenty.
The TCU was mapped by Eurocharged and the ECU was remapped by West-Tuning 398hp & 412lbft on the dyno.
I'd say the car is worth around 13K as it is the best C55 out there, doubt there are any better out there...
If anybody is interested and needs to know anything about it please let me know, I'd be happy to help.