Westfalia make the towbars for UK X3's so assume it would be the Euro spec. Don't know what you consider expensive but indipendant fitters here (UK) charge £570 whereas BMW dealers charge not far from double that and dont do the job themselves - they send the cars to indipendants then add their cut!.

It has removable hitch (swan neck) which requires the SE rear bumper that has a piece that clips out for when you put the hitch in. This means the bumper doesnt need cutting at all.
Its 13 pin electrics so if you dont have them (I dont) you need a 13 pin to twin electric converter.

You also need the BMW loom which you plug in that stops the rear sensors activating when the hitch is attached. (And shuts fog lights off plus ensures the anti-snake option is enabled).

The towbar and electrics plus 13 pin twin electric adaptor is about £300 here to buy and the BMW loom is about £100. Dealers allow roughly 5 hours for the job - so imho the indipendant price of £570 in the UK is ok with warranty aswell.
The BMW price is a rip off.

HTH.