How do we value our cars?

There has been $4.600 put in my Sedan, I have it covered for $7.500.
Not to much nor to little for a 66 Valiant Sedan that I have been driving and enjoying
I looked at many A bodies that I could replace mine with and $7.500 would be enough.
Grundy took pictures and agreed on my value and said I can make it higher as I keep working on it.