These might be an alternative that you can get locally. I bought some at costco.
http://www.amazon.com/Sylvania-DOT-S...0016844&sr=8-1
I use 'em biking and kayaking - I don't really know how long those batteries last as I've never had to replace them. And I don't know how they compare for brightness... They do have a flash mode.
I did have some kayakers one night tell us that they could see us a long ways away with them on.