Is an 89 560 sel a good deal?

I'll be looking at a 1989 560SEL tomorrow that has 156k miles on it. The asking price is $7,900. The car looks very niice and the dealer said " it was owned for the last nine years by a mercedes mechanic".

What should I look for when looing over the car?
Are there any real problem areas?
Is 156K high mileage or do they go much higher.
What Kind of repair costs can I expect?
What MPG can I expect, I'm assuming hight test.