I am the same age as you and looking to buy a MB also. My price range is alittle less around 7-8k. I would stay away from any of these cars unless you are willing to do some work yourself and have a good understanding of most of there systems. I would like a 560SEL too but they get bad gas mileage. I feel the 420SEL is a better choice. My first choice is a 300SDL or 300D cheaper to run and less cost for fuel. For 9k you will be looking at the best of the W126. You should be able to get into an early 90's one with under 100k on the clock. I would think a mid 90's C class or E class would be a good choice also. I don't think you can get a W210 for 9k. It would have to be a killer deal. The cheapest ones I see are like 11k and tired. Do some research on this site. Also autotrader.com.
I do all of my own work so maintaince for me is the cost of parts. If you do not maintain your cars well or pay someone else to do everything I would not recomend an older luxury car. The V-6 Camry could be a good choice. Also don't assume that because the LS400 is a Toyota it will be cheaper to maintain. Parts for these cost big $$$. Good luck with whatever you chose.