You can buy the parts from a dealer, but they will charge you more than anyone else.
Fastlane will sell them for less, shipping included, than the dealer will sell them for, including sales tax, and there are many others who also discount parts.
Mechanics like to take things apart then put them back together, but if you pay careful attention to how they came out and compare to the new parts, you can do it yourself and pocket thre $80.00 per hour plus sales tax.
Get some sunroof paste wax as well. There is a belief that a lack of this causes these things to break in the first place.
Semibodacious Transmogrifications a Specialty
1990 300D 2.5 Turbo sedan 171K (Rudolf)
1985 300D Turbo TD Wagon 219K (Remuda)
"Time flies like and arrow, yet fruit flies like a banana"