[barnettracing]

Originally Posted by andrewc

Use electro-luminescent sheeting as a backing.

http://www.posterpoweruk.co.uk/page5.htm

Peter, as Andrew says, why not use one of those sheets as a backing to a traditional pit board and then buy a spare set of numbers and cut them out (leaving the black surround with a number-shaped hole). The light will then shine through these creating a lit sequence of numbers/messages.

That should give you a reasonably cheap (£50 plus your own work?) solution that is no bigger than a standard board.