It works well with the WSF material. Nowadays,
single RGB LED's are available with built-in circuitry to cycle through colors. You can simply place a cr2032 battery between the leads (like an LED throwie), and that will go by itself for a few days of constant use.
If you want something more permanent and controllable, there are
screw-in style full-color LED fixtures with remote available at absurdly cheap prices. If you want to roll your own and write your own custom program with multiple channels, etc, you could probably put something together from
Adafruit parts/kits for less than $50.
Personally, I would love for Shapeways to offer LEDs, cr2032s, and magnets (essentially the components of LED throwies, which are available dirt cheap in bulk) the same way they had earing hooks and necklaces. I have run this by some of them and response was lukewarm, but I'll bet a handful of nice examples would be more convincing.