My favourite Christian bookstores are not mentioned on the list:
http://www.banneroftruth.org/pages/home.php
http://www.tabernaclebookshop.org/

but I also quite often order via amazon.com (especially when buying books in America) because the postage is quite low (I live in Europe)

Sola Scriptura! Solus Christus! Sola Gratia! Sola Fide! Soli Deo Gloria!
Total Depravity, Unconditional Election, Limited Atonement, Irresistable Grace, Perseverance of the Saints