I was looking for the same type of input... what expenses are out there for X5s over 100-150k miles?
I have 159,000 on my wife's 01 3.0. We love the truck and have a hard time even thinking about getting rid of it, but lately expenses have been adding up and I'm wondering what else will come down the pike.

I feel like I’ve had just about everything…

Last few months:
Radiator
Radiator hoses
DISA Valve
P/S Pressure Hose
Belts
Water Pump
Exhaust Bracket, bolts, and anti rattling clips
Intake Sensor
edit.... I forgot the washer fluid pumps I put in (myself)
Last few years
Expansion Tank (Done myself)
AC Final Stage Blower (Done myself)
Front Two CV Boots
3 Window Regulators
O2 sensors
Welded the tail light that corroded (Done myself)
Valve gasket
Regular Maintenance
Rotors and Pads (Done myself)
Oil (Myself for cost)
Lights (Done myself)

Her tires won’t make it another year, and I need to decide if I’s worth putting another $1,000+ into the car (if not more unexpectedly)

Thoughts…???