2002 puddle light replacement part

I have a 2002 Tahoe and the driver side puddle light in the rear view mirror stopped working. I was able to take the passenger side box and use it on the driver side. I went to the dealer and was told the part would run about $80. I couldn''t believe it was that much for a small plastic box with a light bulb in it. Worse part is I can''t get the box open to just replace the bulb(screws rusted).
 
Anyone know were I order just the box and not pay $80? Can''t seem to find anything on the web that doesn''t include the entire mirror as well.
 
Thanks for the help.

Welcome to the Tahoe forum.  Can you drill the screws out?

I was able to get one of the screws out by hand (lot of work) but the heads of the screws started to shred.