Could anyone recommend sources for evaluating and pricing old sets
and/or single issues of old and/or rare periodicals?

Most of the sources I've looked at, including an older Bookman's Price
Index, seem geared to books.

Is there an equivalent for periodicals?

Most appreciatively to the good serials folks on Friday the 13th ...

Diane Gallagher
College of the Holy Cross
Worcester, MA 01610

Internet:     Lib_Gallaghe@hcacad.holycross.edu
Bitnet:       Lib_Gallaghe@HLYCROSS.BITNET