They usually run about $1 to $1.50

Links:
White, 8 hour, $.65/ Each http://www.grainger.com/Grainger/items/5HM90
Green 12 hour, $.65/ Each http://www.grainger.com/Grainger/items/5HM89
Orange, 12 hour, $.59/ Each http://www.grainger.com/Grainger/items/5HM88
Blue, 8 hour, $.65/Each http://www.grainger.com/Grainger/items/5HM92
Yellow, 12 hour, $1.27 Each http://www.grainger.com/Grainger/items/5HM93
Red, 12 hour, $.65 Each http://www.grainger.com/Grainger/items/5HM91



Enjoy