Just wanted to let everyone know that Comet Pinball recently started selling Spotlight Kits: http://www.cometpinball.com/product-p/spotlightkit.htm. Comes with everything you need: bulbs, reflector cones, hex standoffs/spacers, three different ways to connect to power, wiring, and more. No soldering required.
Singles are $15.99, and doubles (shine light in two different directions) are $19.99.
Most people tend to set these up on the slingshots, where they add a dramatic amount of light to the middle of the playfield. The double spotlight is great for aiming one light up the playfield, and the other down at the flippers.
Enjoy!