Gallery lighting help

dragon0103

Hi fellow grinners! I just ordered my first series (4 photos) to be mounted on 1/2" thick gatorfoam that will be hung on an interior wall. The 4 mounts are 16 x 24 and I am trying to come up with a way to properly light the photos without having to install track lights or direct wire lamps into the wall. I was thinking battery powered clamp lights, but I have no experience with them. How much wattage do I need to properly light a photo this size? They seem to be quite costly ($60 - $90 per lamp) and I would like to save some money if possible. Do any of you have any suggestions?

Thanks, Ryan.