Looking at this today - E320 2004, advice needed

We are considering changing of the car, basically the 210 is roting in more places than i first thought, and at an alarming rate. This added with a few other issues means that long term either i need to throw an obscene amount of money at it, or change cars.
Now i am no oil baron, and i have a very meagre budget of around 8k, so choice is limited especially as it needs to have memory drivers seat and electric heated along with 7 seats. The rest of the options are luxuries.
Now we have seen this
http://www.ebay.co.uk/itm/Mercedes-B...ht_1098wt_1401

but i have very or no knowledge of the 211. I assume the engine etc would be the same as the 210 on this age?
What should i be looking for as a guide to if its a good one or a lemon apart from the obvious?

I have seen some later models at around this money, but they have far more miles (110k+) or lower spec, 5 seat and no extras that we wanted. we need to buy from a dealer, simply as the wife does not want a repeat of the last episode and to make sure that at the very least the 1st 3 months we have a way of giving back the car should we find big problems, but also being able to put a longer warranty on it?
Any advice is always welcome!
Stu