Besides the C32 what are a few of the most expensive options available? For example maybe Nav, AMG wheels, AMG trim, A/C seats, designo, parking sensors, sport options? I would like to find one fully loaded but I'm not sure exactly what to look for.

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1999 SL500
2003 C32
2002 S55
2004 S430
2003 E320
2004 E500

Not sure which options was available in the US.
Not sure which option/standard in the US.

But most expensive in Europe for 2007 C-class (w203):
bi-xenon lights
navi (command APS)
parktronic
leather upholstery
Harman/Kardon LOGIC7 audio system
AMG wheels and AMG Sportpaket (standard for "Sport" versions in the US)
glass moonroof
memory feature for el. seats