My glass got so bad I couldn't see out the mirrors.  I took the car down to
the local autoglass supplier and had them make me a replacement.  $20 and a
half hour each side and it was done.  If you want the right side done with
the special concave glass, then it cost$ much more.  I used regular glass.  
Worked for me.  The guy let me in the shop and I watched how he did it.  
After cutting out the mirror to approximately the right size, he used a large
belt sander to do the curves and bevel the edges.  Some people may be able to
do this themselves.  He also had some special adhesive which was kept in a
heater that he used to glue the new mirror on top of the old.