Ace Wigs (http://www.acewigs.com/)
PO Box 33
Camino, CA 95709
Phone: 800-226-4668 or 530-647-9444 (10 AM - 4 PM PST)

Best Wig Outlet (http://www.bestwigoutlet.com/)
13909 Artesia Blvd.
Cerritos, CA 90703-9001
Phone: (562)926-6002 or (800)715-5003 (Monday-Friday 9AM - 5PM PST / 12PM - 8PM EST)
Fax: (562)926-6005

Lacey Costume Wig
318 W 39th St, 10th Floor
New York, NY 10018
Phone: 800-562-9911 or (212) 695-1996
Fax: 212-695-3860
Their products can be found in the costume shops, usually in a plastic bag with some sort of thick paper labeling inside. Fairly good quality. Ace Wigs above has a listing if you check the View All Brands listing.

Online Wig (http://www.onlinewig.com/)
1252 Black Rock Turnpike
Fairfield CT 06825
Phone: 203-332-6294
Fax: 203-332-6294

Pony Express Creations (http://www.pony-ex.com/)
9350 Trade Place
Suite C
San Diego, CA 92126
Phone: 800.488.5617 or 858.536.2400
Fax: 858.536.2401

wiG (http://www.wiggirl.com/)
Milwaukee, WI
Phone: 1-800-346-4199
They sell rather wild off-the-wall faux fur wigs/fur hats. The model for wiG's site? Her grandmother. Must see to believe…

Wigs.com (http://www.wigs.com/)
2501 Oak Lawn Ave.
Suite 400
Dallas, TX 75219
Phone: 1-800-581-2001 or (214) 827-2008
Fax: (214) 722-1230
Web2: http://www.about-wigs.com/
They've got wigs galore, under all sorts of categories, including some rather strange ones. They have a retail store as well.

Local costume shops will always have at least some stock of wigs.