Although I think they are gouging, some of it has to do with economies of scale. Those $20 flashlights are made in great quantities, so the cost per light drops. The bike lights are made in smaller quantities and higher price per light to make. Also, with new items, prices are high until someone comes out with something similar for a lower price (competion).
But, They are still way too expensive for most people.

Just my 2 cents....

Todd