Clip on LED lights are great..I used to have a bunch lying around the house..picked up at $1.
The challenge is: clipping it onto something! The ereaders have smaller and smaller frames.. and having it in a case helps to have something to clip it on to.
I used a clip on light for PRS 600 and PRS 350.
I have used the integrated light / case combo. Adds a bit more weight (at a min the AAA battery) and size to the overall reader.
But either way .. the key to using it is trying to find the best position that will illuminate enough to read without glare.
Often annoyed I end up sitting next to a lamp or reading from the ipad.. (just can't read long time on the ipad)
There are tons of LEDs clip on lights.. one bulb, two bulb etc.
but keep in mind replacement batteries.
cheap option:
http://www.ebay.com/itm/FLEXIBLE-BOO...item3cc5345baf
I have had much success with this one>
http://www.ebay.com/itm/Great-Point-...item19cbe02720
You can loop it into the clip for compact storage!
two led
two cr batteries..
last a long time
Amazon sells it for 15$
http://www.amazon.com/LightWedge-Cli.../dp/B002VEC47A