I've gone through several, had an AWESOME 3w single bulb LED mini flashlight before that was easily as bright as my 3 cell Maglight (3w LED as well) but in a very small aluminum housing, but it uses CR123 lithium camera batteries which cost around $12-15/pair... at the rate that it ate batteries (a set a month easily, usually 2), I stopped feeding it pretty quickly. It now sits on my computer desk as an emergency flashlight.
My current carry light is one of those cheapy $8 1w 2 AA single bulb LED mini flashlights I grabbed one time in the grocery store on my way out camping, because I carry a couple dozen AA batteries in my truck at any given time since my digital camera uses them too. Its not quite as bright, but it gets the job done just as well - and the best part is that I only have to change the batteries once every other month and AAs are cheap! The only thing I dislike about that particular light is that its a twist-on style, instead of a push button, so it works its way on all the time in its pouch. I usually end up changing the batteries more because it sits on for hours on end, rather than dying in use, but it still only kills the batteries every couple months. For me, its been far more valuable than the expensive, ultra bright one that collects dust at home. Just my .02 LR