Stealth222

2003 S350 it has about 99k miles
The car drops on all four corners overnight, the owner was told to replace rear left strut. The car would not raise when engine is started; I took the car for a drive and it would raise after 2-3 minutes of driving to normal height. What could cause it to drop on all 4 corners? leaky strut or faulty valve block?

Overall the car is in pretty good condition other than the above issue. Is is worth buying and fixing?

Out The Benz

My first question would be the price of the s350, and in most cases of the airmatic suspension sagging to that degree, the best bet would be to replace all four struts.

Stealth222

Price is $800. The owner said he took it to a shop again and was told to replace both front struts.

Out The Benz

So overnight The car drops on all four corners, and when the owner took it in he was told only the front struts needed to be replaced? I'm not too sure about that. I mean you could replace JUST the front two but leaving the rear struts the way they are will end up in a catastrophic failure of your Airmatic pump. Since there is a leak, which isn't always in your struts. It could easily be the valve assembly, o ring seals or the level control valves, but whichever way you look at it, your Airmatic pump will eventually burn out, and will end up costing you much more time, money and headache.
Now to answer your original question, Yes I'd buy the w220, but that depends heavily on whether or not you're a DIY kinda guy. If so, then go for it! If not this will become a very costly experience, VERY QUICKLY. I will attach a video about what you should do when you have a leak in one of your struts and how to fix it.
A mentor of mine once said, "If you got the money why do it yourself?"
so i responded with "if you get everything done for you, how will you ever learn to do anything for yourself?"
How to replace the struts your self
https://www.youtube.com/watch?v=pO533mndN-M&t=158s