This forum, and many private conversations I have had, explain why the 600SL/SL600 is so cheap. Same reason the Porsche 928 is cheap. Expensive to fix and frequently the victim of deferred maintenance from second or later owners who could not pay the freight. Plus a rarefied parts market.

Maybe an SL500 with a quick badge change is called for?

BTW, the front Bilstein shocks for my 560SEL run ~$60 each and last at least 100,000 miles, the accumulatrors for the rear hydraulic suspension cost $100 each and last at least 80,000 miles. Makes you think about those $900 shocks, no? A 560SL (much the same cost to fix) may be a viable option at $20k for a mint, low mileage example. Then again, you might miss the super expensive electric/hydraulic top parts....