I was alerted to this Rootsweb Genealogy Materials Mailing List via another mailing list. Subscription required.
"...Anyone with an interest in the buying or selling of new or used genealogy materials (e.g., books, newsletters, CDs, magazines) in United Kingdom and Ireland. Publishers of newsletters, books, or other materials relating to genealogy are welcome, as are resellers of any form of used genealogical materials, be they businesses or individuals cleaning bookshelves. Purchases are arranged in private posting between the buyer and the seller rather than on the list. NOTE: Commercial sellers please limit postings to one a month..."