I am searching for suppliers, wholesale or retail and preferably in
the US, of flexible metal goosenecks like the ones found in some desk
lamps. I can find the type used in microphone stands, but the tube
diameter is larger than I can use and they are too short. Products
specifically made for use in lighting are ideal.

The goosenecks I am seeking must be 3/8" (approximately 10mm) in
diameter or less, and at least 18" long. Silver or black colored are
best.

umo..

Well, since I found your E27 screws, I thought I would give this one a
shot and I have to admit, a bit easier finding suppliers of gooseneck
tubing.  There are several manufacturers and suppliers of this product
in the United States:

Uniprise International
Spiral Metal Products Division
P.O. Box 369
Terryville, CT 06786
860-589-7262
http://www.thomasregister.com/catalog.cgihttp://www94.thomasregister.com/olc/uniprise/

Vermont Flexible Tubing
Lyndonville, Vermont, 05851  
802-626-5723
http://www.vermontflex.com/

These are only two of many, but I feel they should be able to meet
your needs.  If you check the reference I have listed below, you will
find an additional 100 or so flexible hose manufacturers.

Thank you for your question.  If you need any additional
clarification, please let me know.

Regards,

-THV

Search Strategy:
goosenecks flexible for lighting -lamp

Reference:
Hose Manufacturers EZ-Search - Flexible Metal
http://www.hose-ez.com/hose/0005117_0026069_1.html

Hit the nail on the head with this one. Free samples are on their
way...can't ask for much more than that.