Actually sounds darn cheap if those are self leveling struts. They're almost $600 each through FastLane.

For the 140s without self leveling struts (a US spec 92 500SEL should have self leveling suspension), $100 each for Bilsteins is a decent price. Factor in shipping and installation and $500 is steep but not highway robbery.

Sixto
95 S420
87 300SDL