I really don't know as I have an e38, but you need
to find out if it's the lower case cover or if it's one of the upper ones. The TIS is not to good but it makes it seem as if the lower one is MAJOR work. Maybe if you can tie it down more a service advisor could give you an indication of manhours and then you might talk to some Indys. Oil is cheap and unless it makes a big mess for you where you work or at home you can stand a leak that you only have to top up once in 2/3 months.