Not a bar-end light, but FWIW, I am satisfied with these:
http://www.amazon.com/Light-Sunlt-Fr...dp/B004E3R2W8/
http://www.jbimporters.com/web/check...t_number=95589 (can be ordered thru your LBS if you prefer)

I just attached a couple around the head tube, one above the other, one facing to the left and another facing to the right.