I had a Crankcase Ventilation Valve (CVV) problem (oil leak) on my 2003 X5 4.4, that I resolved a while ago (turne out to just be the top hoses), but in the process of researching, talked to friend who's friend is a BMW service manager in Canada. He recommended a heating collar part number 11 61 0 390 846 that is an update. Apparently useful in extreme cold if you are taking short trips and get condensation. When I spoke to the BMW parts manager here in Denver, it was overkill for my problem. Simple replacement of the disintegrated vent hoses under the acoustic engine cover did the trick for me. Just passing this on as that sounds a lot like your problem. The numbers quoted for the repair sound ridicuously high and more in line with an engine rebuild than fixing the oil separator and lines.