994 euro for 2.2 tax per year

520d's are probably the dearest e60 you can buy after the 535d but if he buys an se over a sport he should get one around 25% cheaper maybe even more

Extremely common problem is timing chain failure on them so budget it into the price or if you could get one that had it done even better

Other common failures on them are dpf's and idrive (this was fixed in later models)

Im sure some owners can give you more info on them as i know little about e60's and even less about diesels

Have a flick through this http://forum.bmw5.co.uk/topic/84323-e60-buying-guide-help-needed/