Can I please have the last seven digits of the VIN number?
I wanted to verify that you had the N62 engine. Unfortunately I do not have great news for this type of failure. While the crank case valves can be replaced first to see if the smoking will stop, the normal failure is the valve seals. This means the cylinder head have to be removed for this repair. I have seen a recent run of these at my shop recently. It seems to be at around 100,000 miles or so that this develops. I have fixed about 6 so far and after the valve seals are replaced the smoking stops.
I would call around some local shops to get quotes to compare pricing for this repair. This would enable you to find the best price. The only thing is that this repair can be a bit complex on a BMW and that is why most people opt to use the dealer for this repair, but a specialty BMW shop (non dealer) may also be able to do this repair at a much lower price.
I hope this information is helpful. Please accept and I am sorry to hear that your vehicle has this issue. Best wishes with your repair. Thank you.