You are probably already framilar with the Power Steering pump issues in the W124, the 500E/E500 have the same problems.
My 92' has over 164k miles and is still going very
strong. As the mileage increases, here is my list of things to be on the look out for;
1. Power Steering pump leaks - new replacement $850, rebuilt $450.
2. Transmission - check for any noises such as a clicking sound while moving in reverse gear, annoying but no breakdown potential - rebuild $2k. Also the typical leaks from Mercedes tranny's.
3. Check to see if the plastic timing chain guides have been replaced, they become brittle after 100k miles - parts are cheap but the labor is not.
4. Belt tensioners tend to go after 100k miles - replacements are under $100 I believe.
5. Motor mounts will need replacement around 100k miles - replacements are under $300 plus labor??? You will know they need attention it the car vibrates noticably at idle.
6. Air pump will start making a sort of worn bearing type of noise - rebuild is around $500, not sure for new.
7. Check the steering slip ring, when turning in the parking lot you will hear the grinding noise, W124 typical replacement.
8. And the No.1 thing which has just shown its ugly head to my, the Air Condition System which has just plain quite operating - may be the electric blower regulator which is $300.
9. May as well mention the wiring harness issue. The insulation can become brittle exposing the wiring around the fuel injector area - cost is around $1k.
10. The ASR systems may exibit a symptom where the ASR light will stay on while driving - usually points to the Throttle Body Actuator I believe, that can be $1k.
11. Some parts on the Self Leveling Suspension (accumulator) usually need replacing around 100k - cost is not that bad.
12. Interior misc parts which are typical of other W124 cars.
So there is my list, some of the other guys will have further details I am sure. Also, try running some searches, many things can be learned in addition to my above list although I think I have covered every big $$ issue in regards to this car.
This is not intended to scare anyone here!!
These cars are very robust considering the performance they deliver year after year! I have only put 5k on the car but there is no oil consumption to speak of. At least half the things I mention above are issues on other W124 cars which you are probably already framilar, I just thought I would try and make my list complete.
I am sure after your drive tomorrow you will be quite surprised at how well the 500E can do everything! It can cruise all day long and never disturb the passengers, and when you are feeling alittle frisky, well..... I like to use the term PermaGrin
to sum up the driving experience.
I think the price sound par with the miles, you might try and get a carfax just for information purposes. Also, you might try contacting all the Mercedes locations the car has been serviced at and request that they forward the cars history to you, the records may or maynot be complete?
Hope this helps! Sorry for the long reply.