You may get lucky finding an unused BMW shock, but you're not really going to know what you're getting, and as Lee stated the shock is going to be 16+ years old (so the seal is holding up fine on the shelf, but what about when it's on the bike?).

Quote Originally Posted by 98lee View Post
Buying a new (still available) one from the dealer for $1100 probably makes the most sense.

I would go aftermarket for that price... you can get a brand new, fully-rebuildable front AND rear, with a 5-yr warranty for almost that price. (Just checked Pirates Lair - no affiliation)

Or find a used aftermarket shock and get it rebuilt. Either way, the bike is going to handle much better after a refresh.