There should be aftermarket non-SLS struts available, I know they make them for later S classes and other vehicles with SLS systems like the Lincoln Mark VIII. If you wanted to go that route you would likely save a bundle of money, but unfortunately I don't have any links off the top of my head to give you.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth