This has to be one of my favorite collars that I have made so far, This is the prototype, although I don't think I am going to change the design much. The collar has 12 LEDs in it and they are extremely bright and they run off of 2 coin cell batteries which are easily replaceable. The battery back is on the inside of the collar next to the buckle and measures 2in by .9in and .25in thick and is easily concealed. I can get White, Blue, Green and Red LEDS and can do the collar in almost any color. If I use a darker color I can run a white strip on the outside for the light to shine through similar to the two-tone collars

This will run $35 Shipped. Battery life is suppose to be around 8 hours per manufacture.

http://www.furaffinity.net/view/7298411/ (White instead of black.)
http://www.furaffinity.net/view/9966148/
I also have the electroluminescent collars
http://www.furaffinity.net/view/8312086/