I ran a 2002 BMW for a four years. They have adaptive service intervals: the frequency depends on how you drive them. For me, it was rare enough (every two years?). Regular servicing wasn't cheap, but wasn't outragously expensive either (unfortunately I can't recall how much). The big benefit was that abosultely nothing went wrong with it in all the time I had it. If you look after them, they should all do this.
If it has a main dealer service history, it would be a pity not to continue with it. If not, I'd search out a good independent.