This has become a fun experience for me as I have restored old pictures for people. I've done loads of research in pricing this service and I have come to a fair conclusion which I have categorized below.
Moderate Repair - Remove residue, blemishes and spots, discoloration, scratches, and worn edges. Repair minor tears, fading, creases and partially torn photos with no missing pieces. Adding background and improve contrast................$40
Extensive Repair - Repair more creases or tears, remove unwanted elements, change background, fix some missing areas and/or replace or move key elements. Repair also any dust, scratches, blemishes and other minor problems............$55
Severe Repair - Repair severe discoloration or fading, severely damaged edges, major creases & torn photos, add background, fix severe stains. Reconstruct missing pieces or facial damage. Fix scratches, spots and/or blemishes....$70-100