Colt Derringer question

Today I found a pair of Colt 4th model derringers in the velvet lined Colt book storage box , nickel plated and in mint shape, Faux ivory handles , the book has some wear and need rebound but these should be dated back from 1960-63 by the N code on the guns low serial number 4 digit unlike most of the 5 digit I see .
$325 a fair price for unfired matching pair with well used book box ? These are not the actual pistols but pics I found that are identical as they would not let me take pics of them until they are in my hands . I pick them up Saturday

 

I have a few gun value books but still cannot find these . I found a Gun blue book guide online but of course they want you to pay for it but this is all it stated

 

Would this be a used price ? These are supposedly unfired , no scratches or wear marks at all on the nickel plating . These were on consignment and the actual owner claims he has had these since new early 1960's . The book isnt in the greatest shape , Dont get me wrong its not scrap but not mint either I would be looking at $25 to have the original binding fixed its just separated like any normal old book would be from opening and closing it all the time . Will the fixing of the book lose value ? it would looks alot nicer fixed up right though.
After looking around $325 seems to be about the bottom end all the way up to $700 for a mint set with minty fresh book . So I guess I didnt get hurt . Just reassuring myself . I hate getting screwed on what I think may have been a great deal . Anyway thanks for the heads up and if it wont kill the value I'm going to have the spine repaired on it , they quoted me $25-45 on the repair and it will still have everything original on it just a new spine under the cover

 

Here are some better pics I found on line . This book is in about the same shape as the one I bought and guns are about the same as far as unused and shiny nickel finish