Well, you really won't get one answer as to a price.
A collector would more than likely pay double that of what a dealer would pay. Also, an appraisel could be more than both. Plus, you also have to factor in personal value...
Is he looking to sell it, or does he just want to know it's overall value?
Insert witty comment here......
Vincit Omnia Veritas
Vincere est Vivere