Never buy new, always buy used. There is more to go wrong with the W203, I'm sure.
A 2001 is usually in better shape than a 1991. If you ever drove a W124 brand new, it was not like a pickup truck in any respect. That's a real joke!
A C-Class, is a C-Class. The W124 sold for much more money new than a C-Class and no matter what age the W124 is, the value is built into the car.
Condition....everything is condition. The W203 is a nice looker, but pretty small.
Naysayer #1. An E, is an E, and a C, is a C.
Get a W210 instead.