The problem with separate book lights with the Touch is that they don't attach well. There isn't too many places on the KT that a book light can attach without blocking part of the screen. And the shape of the back (rounded near the edges) doesn't give a good flat surface for the light to attach to.
Costco has a Mighty Bright Hammerhead 2 pack that works ok. A big plus is that it uses AAA batteries.
http://www.mightybright.com/Book-Lig...LED-Book-Light
It also looks like Mighty Bright has some specific eReader lights.