I've just about got the first phase of my system build but I wanted to share a few good suppliers I found.
http://www.wolfautomation.com/ These guys have LED pilot lights, although they call them indicator lights, for a couple bucks cheaper than amazon or ebay. They also have good prices on switches. There is a $50 minimum order, but that's not hard to hit just on lights and switches for most systems. I got my back plate from them, too.
http://www.zorotools.com/g/00062830/k-G3266794?srccode=cii_23393768&cpncode=32-217009454-2&utm_source=channel_intelligence&utm_medium=refer ral&utm_campaign=AmazonProductAds These guys had relays for a heck of a lot cheaper than amazon. I'm talking 8 bucks instead of 20-30.