I would like to share my experience with you.

I have 2000 X5 4.4l
Bought it with problems I had to fix:
Water leaking,
Tranny broken,
ABS module,
Timings corrected,
All Seal Gaskets changed,
Thermostat changed,
Both side rear Air Springs changed,
and some drivertain (Names don't match so no point of posting)
Window regulators failed, (only Clip problem)
and little more.

However I love It! 135k miles on it! even though It's 11 years old, I would buy it again After knowing all the problems it had!

EDIT: Water Hose on back of engine and Coolant Bucket due to leaks.
Belts, Fan.