Maybe something that new isn't mandatory to be a stocking item.
You might get the part# from the counter person and do a BMW parts locator search (if there is such a thing).
Is there anything special about the hose? When I come across something odd-ball, I just go to the back of my local parts store and match up something that looks pretty close. I've dealt w/this one guy for lots of years and he doesn't care if I help myself to his selection.
Most places (Orileys, Napa,Auto Zone,etc....) don't have the knowledge to mix and match between makes and models, they can only tell you what's in the computer. The "mom-and-pop" stores know the ins-and-outs of what they stock and are more willing to take an old part and see what's on the rack.
Good luck,
---TEX---