Go to www.abebooks.com, enter Puzo and The Godfather on their search page, and check the listings for first editions. My guess is that even a first edition in perfect condition won't be worth much because so many were printed.
Ntra la porta tua lu sangu � sparsu, E nun me mporta si ce muoru accisu... E s'iddu muoru e vaju mparadisu Si nun ce truovo a ttia, mancu ce trasu.