Hope you understand english. Its e little bit easier for me to write in english as in german.
Maybe J.Deckwer is right and in Germany it is true. But in Latvia (Lettland) a year ago we bought our year 1989 V8 for 1950 euro. It was dirty, the owner had no fuel in tank, no window washing fluid too (ewen no water), visualy it looked badly. But technicaly it seemed to be OK, cause the owner had bought it only 3 month ago and only then understud that he can not afford this car, and it seemed he needed the money deperatly.
And in this year the car has aprowed as a reliable one, cose, the owner before the one from whom we buoght the car had realy cared for it and changed all the parts in time and the original ones. Nothing has broken down until now.

So I guess you have to read a lot of literature befor to by your car, and check all the things that usualy brake down for V8, and maybe beteer go with the car to a VAG and let them check all the systems, so that you are shure, its not in bad condition.