I use a princeton tec rage for a neck light after trying many. Totally waterproof, BEYOND bright, and is 11$ at west marine. I can bring mine to a meeting if you want to check it out in person. Only drawback is the "twist-on"... wish it was push button.
http://http://www.brightguy.com/products/Princeton_Tec_Rage_Xenon_Flashlight.php