The mirror stem will most likely be of more interest than the turn signal housings. I've posted before and after photos ..the mirror stem was in a particularly bad state after some one else had a go at it and left a hole in it
http://www.aclassmetal.com.au/
https://www.facebook.com/pages/A-Class-Metal-Finishers/133288193385505
I won't post the cost on here because it can vary a lot depending on the original condition. I sent some photos and they offered a best and worst price to me and it came to a bit above half way.
They did about four different processes in the job. Strip and polish, repair and fill and a couple of plating processes.
There must be a lot of mirrors out there that would benefit from the process.
Hope this is of interest
Peter