Abgasanlage: What problems to look for on 730d?

[Mr-Heier]

Hey guys!
Im sorry for writing in english but this is the only bmw7 forum i found in the world
I live in norway and i am looking into getting a 2003 730D and import it to Norway. What kind of errors and problems should i look for? Im looking for a car that has gone less than 80.000km.

I have searched mobile and found a few for around 30.000EURO. Is that an okay price? Im also worried about the KM might be tricked with and turned back. Should i not look for the cheapest of the cars on mobile?

thanks in advance for any hints and info

regards

Marius