www.digikey.com [
digikey.com]
Those two places above do sell them, but they are overpriced. Why not just order them yourself and save a few bucks while you're at it?
If you do a search for "Digikey product numbers" or something similiar, you will find a post I created with the part numbers for the LEDs that you will need.
If you order from Digikey as opposed to those other places you could save around $10.