A quick search at <http://www.bibliofind.com>, which lists 8 million used
books, reveals several copies of Poe's book for sale, US$1200 to $1650 for
the first edition (1839) and $600 for the second edition (1840).
 
Poe, Edgar A. 1839. The Conchologist's First Book: Or, a System of Testaceous
Malacology, Arranged for the use of Schools. Haswell, Barrington, and
Haswell: Philadelphia. 156 pp., 12 colored plates.
 
Robert Louis Stevenson did not write a book on shells, but his famous sentence
"It is perhaps a more fortunate destiny to have a taste for collecting
shells than to be born a millionaire" appeared in 1911 in
 
"Lay Morals and Other Papers. Chatto & Windus: London,
 
a first edition of which costs $38 to $125 depending on condition, as listed
with bibliofind.
 
By the way, bibliofind lists two copies of A. Myra Keen's Sea Shells of
Tropical West America (2nd ed. 1971) at $60 and $75.
 
Gary
---------------------------------------------------------------------
Gary Rosenberg, Ph.D.                     [log in to unmask]
Malacology & Invertebrate Paleontology    gopher://erato.acnatsci.org
Academy of Natural Sciences               http://www.acnatsci.org
1900 Benjamin Franklin Parkway            Phone 215-299-1033
Philadelphia, PA 19103-1195 USA           Fax   215-299-1170