Are you talking about this windshield?
I may be wrong but, it is my understanding that this OEM windshield kit is not available any longer. However, the windshield itself and much of the hardware can still be purchased separately if Max BMW parts listings are correct. I don't think the right mount is available new, but you should be able to find one used. It is a very sturdy windshield, but you should be able to find something for much less. This could be a very costly way to add a windshield to you bike. Have you had a chance to ride a K75 with the factory windshield?