Years ago I had occasion to drive one of these, and know what they can do.
The grin factor and driving pleasure they return is unbelievable, trumped only in performance for the W124 by the AMG Hammer and E60.

They are an utter thoroughbred sports sedan, of the highest quality and utmost rarity. They were very very low in production numbers and even less now survive.

Price is driven by demand for them, and these are becoming acknowledged to be real classics that you can enjoy every day.

I wouldn't mind paying $12,000 or even more if I had to, in order to obtain a well sorted, rust and accident free example, in a color I liked.

Thet are such wonderful cars. The S430 is more of a modern cruiser, built to a price point, rather than for discerning sport sedan drivers. Which are you?

__________________
1991 560 SEC AMG, 199k <---- 300 hp 10:1 ECE euro HV ...

1995 E 420, 170k "The Red Plum" (sold)

2015 BMW 535i xdrive awd Stage 1 DINAN, 6k, <----364 hp

1967 Mercury Cougar, 49k

2013 Jaguar XF, 20k <----340 hp Supercharged, All Wheel Drive (sold)