Your book has a high retail value of $200 - $250 on today's market. Signatures in books of this age are not uncommon, as they indicate prior ownership. If you want to complete the set, you would be best to contact various book dealers and auction houses to let them know your 'want list'. When they do get particular volumes from your set, they will contact you.
Here is a list for you of book dealers and auction houses to contact. It is a free service.
White Raven Books, Michigan. C. Hedger Breed (tell him Nora sent you): http://www.whiteravenbooks.com.php53-3.dfw1-1.websitetestlink.com/
Bauman's Rare Books in Manhattan - http://www.baumanrarebooks.com/
PBA Rare Book Auctions in San Francisco: http://www.pbagalleries.com/
Swann’s Auction Galleries: http://www.swanngalleries.com/bo_oks.cgi
Bloomsbury London: http://www.bloomsburyauctions.com/
Heritage Auctions: www.ha.com
Australian Book Auctions: http://www.australianbookauctions.com/
Dominic Winter Auctions: www.dominic-winter.co.uk/
Bonham’s Book and Manuscripts Dept: www.bonhams.com/departments/BOK/
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