I got mine from the dealer. I purchase an after market one before and it was not the greatest plus it did not feel sturdy and durable like the one I got from BMW and did not fit tight. The one from the dealer cost more ($200) but to me it's worth it. Great outside protection from the elements plus the inside that touches the car is soft to protect the paint. It fits nice and snug over the car with no room for it to lift off due to heavy winds.
2008 650 Convertible- 6 Speed manual- Sport package- HUD- Lane Departure- Comfort Access- Merino Leather- HD Radio- SAT