What this guide covers
The cars cited in the threads are a 2001 X5 3.0, a 2001 X5 4.4i, a 2003 X5 3.0, a 2003 X5 4.6is and a 2004 X5 4.4. For the model page see BMW E53 repair costs. Several E53 repairs here have no dealer price at all, and the pages say so.
Driveline: front driveshaft and transfer case
The 2009 thread has a dealer quote for a transfer case and front driveshaft together, an AAMCO quote for the same pair, and an owner who sourced the parts online and paid an independent for labor. A 2021 thread describes a failed two-piece front driveshaft and quotes from AAMCO and a regular mechanic. Most quotes bundle the shaft and the case. See Front Driveshaft & Transfer Case and the BMW E53 X5 Front Driveshaft and Transfer Case.
V8 cars: valley pan, valve seals and the oil separator
On the 4.4 and 4.6is the valley pan leaks coolant. The 2013 thread has independent quotes, and a 2009 thread says the coolant pipes under it are a separate and larger job. See Valley Pan Gasket and the BMW N62 V8 Problems and Repair Costs for the N62 side. The oil separator and crankcase vent is covered on CCV / Oil Separator. Its 2008 dealer and independent quotes bundle other work, so they are not a price for the separator alone.
Engine pages for the V8s are BMW M62 engine and BMW N62 engine. The six-cylinder 3.0 is the BMW M54 engine.
Steering, ABS and the rest
Power steering hoses and pumps are priced on Power Steering Pump & Hoses. The ABS control module is usually repaired by a mail-in service in the 2016 thread, and one owner found a bad wheel speed sensor behind the same lights. See ABS / DSC Module. The BMW ABS and DSC Warning Lights: Causes explains how to tell them apart.
Before you buy
Ask for records on all of the above, and ask what each past quote included. Compare dealer and independent prices job by job; the BMW Dealer vs Independent Shop: Which Is Cheaper? explains why they disagree.