1975 Coupe de Ville value

My in-laws have a 1975 Coupe deVille and they are the third owners of it, they have all original paperwork. The car has only been out of Las Vegas once to go to Jean, NV. It is not in the best cosmetic condition, (needs new vinyl top, new paint, and new interior, including dash all been bleached by sun). Has 108,000 lifetime miles. Motor, transmission and under carriage is all original. They believe as it sits, they could get $10,000 out of it. I would like to know if that is even possible. Could post pic if needed.