[redshift]

I used some prewired leds that came in a 4-pack. I got mine at Advance Auto. Thy come in white, red, green, violet and amber- 8 or 9 bucks for 4 and they already have the proper resistor so they'll work on anything over 6 volts. If you're worried about water, just a little silicone caulk over the back and no worries. Pep Boys and Auto Zone have a decent selection too, you may be able to find the mini bricks that have 5 or more leds for even more light with less wiring.

Don't overcomplicate things :D