I just checked the headlamp I bought a year ago for my CF last April, it cost me less than 30 bucks. Never used it, battery still OK. Bought a normal non-rechargeable battery, shame on me. Tiny LED uses very little juice, blindingly bright. I'll use my phone next time if I need a light - the battery is so huge relative to tiny LED that it's mega-efficient, would probably last a week and it's rechargeable. There are a few things I won't take next time to save weight, headlamp is on the list, I'll give it away. The argument for headlamps is that they leave your hands free if you break your leg and need both hands to read a map (?!) or crawl to safety. Looks like I'm doomed or I'll slobber all over my phone holding it in my mouth.
Mike