My advice is to get a flashlight that uses batteries that are inexpensive and common.
I bought two very bright flashlights, similar in design to the surefires, from Costco for a really cheap price, like $30 or $40 ish. They came with 4 lithium batteries (2 each). The batteries lifespan was short however. When I went to buy new batteries, I learned that the batteries were cost prohibitive so I no longer use the flashlights. Seems to me that it was about $5-10 per battery, which I think is excessive since they don't seem to last very long (in that flashlight). While I can easy "scrape up" $10, feeding a flashlight $10 isn't really that appealing to me when other flashlights function fine on batteries at 10% the cost.
Maybe surefires make their batteries last longer or use different batteries? The key is to make sure they are affordable batteries.
after writing this I saw a the above link for batteries. That may be the best way to go. I can once again afford to feed my flashlights every hour!