You can get lights that will take 18650's or 3 by AAA if you really need to be able to take normal batteries in a pinch:

http://www.amazon.com/WindFire%C2%AE...dp/B00OOER06K/

For the price of a few AA batteries you can have a new 18650 light:

Coco Powerful 2500 Lumens Zoomable CREE XML T6 LED 18650 Flashlight Torch Lamp - - Amazon.com

If you get two or three discharges out of it before the junk fails, you've saved money. In my experience they'll last a bunch longer than that (just don't trust the waterproof claims on the cheap ones).