I feel your pain!
If you are going to order, I wouldn't go with the factory option. It's too expensive and, as mentioned earlier, you can't residualize it anyway. Get an Execuhitch, it's nicer, costs less, and is totally invisible when not in use. Just to give you the most up to date pricing, here's what I got from Execuhitch (last month):
"Thanks for reaching out to me. Our invisihitch is a nice rack-mount solution on the M Sport version of the new X5.
The basic Rack-Only version of our new X5 hitch is $544. It includes our hidden hitch beam with vertical latching mechanism, plus the removable 2" square-tube receiver.
The full tow+rack package adds to the above safety-chain attachment points, a ballmount and ball, the BMW wiring harness with trailer receptacle, and vehicle reprogramming. The full package is $1148.
Although the price difference is significant, many customers want to wire up the vehicle for possible future towing at the same time that they add the hitch. Doing so has an additional advantage for racks -- you can plug a device into the wiring harness whenever you attach your rack and the vehicle will automatically disable the rear park sensors. Otherwise, the park sensors will alarm when you reverse with a rack attached. You can turn the alarm off manually using your iDrive, but you have to do so every time you reverse and doing so shuts off the rear camera as well as the park sensors. So the full tow package sometimes becomes a serious consideration for rack customers."
Figure on 150-450 for installation (lower end if you just want the receiver, higher end if you want it with wiring installed. Some BMW dealers do the install; if you get it done there, of course, increase the prices quite a bit.
Ridiculous. Even with the aftermarket option, you'd going to be ~1500 bucks for install with wiring. That's about what it would cost to put a 20,000 lbs 5th wheel with full electric braking and sway control into a F350. I'm very happy with the Execuhitch product, but the price for it or the BMW option are just outrageous beyond reason. It's a class 2 hitch and a few wires, the markup on the OEM version has to be 1000%. <sigh>
Just an FYI, as I understand it, the factory hitch is available in other locations, but not the US. Not sure why, probably some liability thing. Whatever it is, BMW needs to get over it. All their competitors have a factory installed hitch option that's dramatically less expensive and can be rolled in to a lease. Again, when leasing, we're talking a BIG swig in cost between a factory installed option (that can be residualized) and a non-factory or after the fact option (that cannot). It's not "pocket change", especially when you're dealing with a install that's close to 2K with parts/labor. That number goes straight into the lease, (2,000/36 X interest). If it was factory installed, it would be (even if a 2K option) it would only cost ~40% of that amount because you'd only pay for the "used up" portion of the hitch during the lease.