Samuel Weiser Publications runs an Antiquarian Department
at their York Beach location.  The contact is:

Glen Houghton
Samuel Weiser
Antiquarian Dept.
P.O. Box 612
York Beach, ME  03910
(207) 363-7253
(207) 363-5799 (fax)
weiserbooks@ichange.con

The phone number is different than the normal sales number and they do not
tell you about this shop unless you ask.  Glen has been in the Antiquarian
business for over 20 years.  He seems particularly knowledgeable regarding
older titles with ambiguous translation and printing histories.  I've had
good results working with him.

[from personal email: Mark (aerobic@best.com)]