I had this leak on my car, same burning smell.. but that part is covered on N63.. sorry to hear this... there's an article by igor he did it himself on his X6M. if youre feeling it..
that labor rate is high .. here in cali its $2500 to fix.. i got 3 quotes just got lucky with the N63 CC
http://www.xbimmers.com/forums/showthread.php?t=1067620