I am not sure how deep your scratches are or if it is just the typical pitting/discoloring.
I wet sanded the damage and resealed the assemblies using a $19.00 kit. Took about 15 minutes each side and the results were pretty amazing really. Check out this thread. You can see my before and after photos. If you are looking to save money on the assemblies, this may be worth a try.
Sorry, just realized I never included the link.
Here it is;
http://www.xoutpost.com/bmw-sav-foru...ight-lens.html