Recurring inspection points include whether both keys are present (replacements run ~$300 each, and the door-lock emergency key another ~$350-400) and small missing trim like the front tow-hook cover. The C55's more aggressive front fascia is prone to cracking at the lower bumper, so common that Mercedes offers a repair kit.
Buying checklist: keys, tow-hook cover, and the front-fascia crack
Mercedes-Benz C32/C55 AMG (W203) · buying