Found these at Target-I think $9. A little bit of wrangling with wires and making them not visible from any angle. Oh, and then fixing them 'just so' under the 'map pockets' so that the lights cast a good strong light without the chance of a foot kicking them. And then having my fingers stuck with SuperGlue to that same light.
Worth the effort and I have a friend that-though embarrassed of being in a big ol' Caddy-likes to cruise the interstate while in the back seat watching DVDs in Dolby surround.