Bill, any particular model of Luxo light? They have quite an assortment.
Those manufactured under the "Cheap" brand name seem to work about as well as any. You can find these for $15 to $20 each at most quality stores that stock Cheap Corporation merchandise. The Wobbly Manufacturing Company makes a nice line of Luxo-like lamps. Get the big ones, not the prissy little desktop ones. Figure you'll trash about one per show and always carry a little extra picture frame wire with you to sort of the patch them up as needed.
Wow I just Googled "Luxo lamps" and was amazed by what you can pay online for de$igner Luxo lamps.
Oh I see the problem, "Luxo" is a trademark! Google "
cheap spring arm lamps" to avoid sticker shock.
Here's where I got my last batch.
http://www.staples.com/Black-Swing-Arm-Inc...408203-17334-US