One of the most common reasons for not having a Ghost Light is that they aren't commonly available from theatrical supply houses. All of the Ghost Lights I've ever seen have been cobbled together by well meaning shop craftsmen. The problem with this approach is that whenever you manufacture something you assume the liability for it as well. When you combine this with poor electrical knowledge and make-shift adaptations the results can be electrically hazardous as well as physically hazardous. So where is the safety in that?
Item 212004, Model GL600 (www.lowes.com/pd_212004-337-GL600_0)
[Update 2015-08: This product is no longer available.]
Lowes sells it under their Utilitech brand (made by Cooper Lighting), it is UL and CSA safety listed, fairly inexpensive, and most of all, pretty darn indestructible. The unit has a weighted base that houses the fluorescent lamp ballast, and incorporates a groove around it to wrap-up the cable when it is not in use.
The case is plastic and has a tie loop at the top if you need to hang it up for storage or suspend it. The clear plastic tube that house the lamp acts as a container to keep broken glass off of the stage should you give it a really significant whack.
Fortunately, the unit does NOT come equipped with a lamp (yes, this is a GOOD THING). When you outfit it with a lamp you can choose the color temperature (CCT) and color rendering index (CRI, or Ra) so that it doesn't clash with your other work lighting, and if you elect to beef-it-up a bit you can install a hard-use lamp like those made by ShatRShield (www.shatrshield.com/catt8page.html)
This unit uses less than 40 Watts of power and lights-up a pretty good area around the stage, so pop one out onto the proscenium line so nobody has to grope in the dark and fall off into the orchestra pit. That's a dangerous fall to make unexpectedly, and many people over the years have been killed or received career-ending injuries this way.
Ghost Light to be effective, it must be left ON. You have to twart them at their game. What can you do? Post a sign at both the on/off switch on the Ghost Light AND at the end of the cord(s) that supply the power. Be polite, but be firm.
"I want you to meet my little friend." said Al Pacino's character in Scarface. This will confuse the energy Nazies for sure: Add a photoluminescent tube over the lamp. This will continue to glow for about 40 hours after you remove the power from the lamp - so it will give any stage marauders a bit of a chance see where they are going should the power go off (or be switched off). The Lumenite® Light Sleeve is a semi-translucent, photoluminescent sleeve that fits readily over new or existing fluorescent tubes.
Do you really want to keep it safe and confuse the Energy Nazies? Add an Uninterruptible Power Supply (UPS) to the Ghost Light. At only 40 Watts power draw, a small UPS will keep the lights on for hours. If you use an LED based lamp, then the darn thing could glow for a day or more.