The Collaborative International Dictionary of English v.0.48:

Bibliopolist \Bib`li*op"o*list\, n.
   Same as Bibliopole.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bibliopolist
    n 1: a dealer in secondhand books (especially rare or curious
         books) [syn: bibliopole, bibliopolist]