I'm considering this puppy. 200lm. P3D which uses 2 x CR123 which you can buy a couple at purchase of the disposible type or get the rechargeable RCR123 with charger and get 4 cells and swap around.

4.8hrs on high or 1.8hr on turbo. And small enough to go on the helmet with not much weight feel.

You can also buy cells from http://www.dealextreme.com and everything on the site comes with free S/H. Many Candlepowerforum members have commented many good deals, transactions, and products from the site. Free S/H (worked into the price anyways) is good stuff.

Those CR123's if memory is correct have a 10yr shelf life so keeping 2 disposibles in the bag/pocket and you're good to go when things go sideways.