I haven't got one, but i have just fitted one myself. The brackets don't slot into the roll bar covers, they are screwed through the covers into the plastic beneath. I got a deflector off e-bay and bought the brackets and screws from my dealer. I also bought the brackets to fit the deflector into the bootlid when not in use too. The brackets and screws came to 25 quid. I was told i would need to buy new roll bar covers too, at a cost of 72 quid for 4 pieces.
I paid for the covers and used them to create a template for the holes, then i transfered the template to my covers ( still on car) and drilled the holes out. I tidied the rough edge with a knife and fitted the brackets with the screws provided. I then took the roll bar covers back for a full refund, and saved myself 72 quid.
Don't know how much the main deflector is from BMW as i didn't need one, but the small screens that go in the roll hoops are 48 quid each!!!!
I decided not to fit these as my headrest are set quite high and it seems to be ok.
If you need more details on the fitting, let me know.
Daz