General Links:

Church Libraries Magazine

Author Websites:

Douglas Bond

Elyse Fitzpatrick

Harry Reeder

Carol J. Ruvolo

Fine Online US Retailers of P&R Titles:

Amazon.com
Alliance of Confessing Evangelicals
Biblical Counseling Books
Christian Education and Publications (PCA)
Christian Book Distributors
Crown and Covenant Publications
Cumberland Valley Bible Book Service
Evangelical Bible Bookstore
Grace Truth Books
PCA Christian Education and Publications Bookstore
Still Waters Revival Books
Westminster Seminary Bookstore

(Note: This list is not comprehensive and consists mostly of merchants who maintain an online presence.)