Heh, this ranks with my Missing Soda Pop mystery dream.... But what a find--Bonanza graphic novels! I'm curious if such a thing exists, too...

Trackdown... I am not familiar with that. Any names in there I might recognize?

And yes, there is nothing quite like a bookstore--especially a secondhand bookstore. You never know what treasures you'll find in there. Like novelizations of lost Doctor Who arcs..