I have the standard chrome window trim on my 2003 E60 and wanted the matt black look of the shadowline trim. I spoke to my local stealer and they quoted me £611 (parts were £178ish.
I then found a website in the US who sold matt black tape to go over the trim so bought a role for $20 but it is really fiddly to put on.
I then came across the following how to guide to paint the chrome trim myself http://www.pelicanparts.com/bmw/tech...30_3Series.htm
Now I am no expert in these things but i've done the bottom 2 strips on one side and the result looks awesome, as good as the proper trim I think. It took me longer to tape up the bodywork around the trim then it did to paint. I bought some professional matt black trim spray paint and primer from fleabay and some decent masking tape. I lightly sanded the chrome and applied 1 coat of primer then 4 or 5 very light coats of black to build up. Today was the acid test when I took it to my local hand car wash who use very powerful jet sprays, I was a but worried they would strip the paint off but everything is OK.
So for £20 in materials and what will take me a day to do properly it's saved me a whole lot of money, I think i'll do the front grills as well