eBay sells a variety of high-power CREE T6 flashlight that use a rechargeable Li-Ion battery (similar in size to the non-rechargeable SureFire flashlight batteries) that are surprisingly bright and amazingly cheap.
I've bought several from different sellers based in China and the designs are all remarkably similar - rugged all-aluminum construction and probably made by the same manufacturers but sold under different brands.
This particular one (
2000 Lumen UltraFire) comes with both a battery and charger. I'd advise buying additional batteries as quality control on the batteries is not quite as good as the flashlights themselves and about 1-in-4 turn out to be clunkers; i.e., don't charge to the full voltage and/or don't hold a charge.
You can also buy them that are crazy bright (I bought a 32,000 LM light for about $45 including S&H), adjustable beams, multiple LEDs, dual-brightness, etc. Delivery has been anywhere from a few days to a couple of weeks.