I've bought quite a few over the years, from deal extreme in china.
I didn't bother with the ones that run off AAA batteries because they go flat too fast. They suck up about one amp.
I get the ones that take a lithium rechargeable battery type 18650, usually around 2500 milliamp hours capacity. (they say, but they never are. Usually about half that or less at the current required.
You can have a look at them here.
www.dx.com/p/e17-cree-xm-l-t6-900lm-5-mode-memory-white-led-zoomable-flashlight-w-bike-mount-black-2045377.html The 18650 battery is the one used in the old laptop battery packs. I pull them apart and pick out the good cells when the battery pack has carked it. They still run the torch for an hour or two, depending on how carked it is. The pack has 6 cells and you usually get about 4 or 5 good ones.
You can also buy the cells form deal extreme but they take ages to get here due to not allowed to transport by air.
You MUST have a proper lithium battery charger to recharge each cell. An ordinary charger will blow them up. Absolute maximum voltage of 4.2 voltage. Anything over that goes pyrotechnic. DX sells those as well,. about $12 I think.
I've bought lots of stuff from them and never any problems.
Some of the torches are better than others as far as brightness and battery drain goes.
The three mode ones seem to be the best with the CREE led , xml t6 I think.
The 5 mode ones have too many modes to click through to get the mode you want.
The three mode is bright, dull and flashing.
Anyway, they're cheap so I buy some of lots of different sorts.
I lose them so often I need lots.
Oh,.. but they don't float. Straight to the bottom they go, but if it's on then at least you can see it,. for a short while, down at the bottom of the muddy drain,.. blinking away,.. save me,. save me,.. SOS,..
(oh,.. I'm so embarrassed . But I kept running over bobtails in the dark. 
