...Amazon is running one on the Surefire X300 weapon light right now, which is pretty much the gold standard for pistol lights. They are just unbelievably solidly built.
(The main reason my backup M&P sports a Streamlight TLR-1 isn't because I think it's better, but because I think it's reasonably good and it was almost a hundred bucks cheaper than the Surefire unit. But at $159 for the X300 instead of the ~$200 they usually bring? I'd have picked it over the TLR-1 any day of the week and twice on Sunday.)