For the trekkies under us:
The "Borg" earlight
Find it
here
It uses two CR2016 button cells and lasts 18 hours. Price $12,00
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Here is another one:
Find it
here
This one uses one AAA battery so that's a big advantage over the Ear Light that uses two button cells. It lasts 25 hours. Price $24,95.
You can find the "same" light under a different name at
Curcuit City but instead of $24,95 they charge you $2,99. It looks the same but it could be that it's a cheaper imitation.
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This one looks good also:
Find it
here
It also has button cells but this one uses CR2032 and I can get them for free on my work. It lasts 36 hours. Price $12,95.
It's clear you can get a lot of these ear lights on the internet and I think it could be better instead of trying to clip something to your Reader. I will go for this type of light. I only need to decide which one. I'm also planning into modifying it so it is possible to dim the light.