I just go with something small and cheap (under $30) with at least a one year wrty and keep the paperwork. Works just as good as a high dollar Surfire. Found usually at a big box store.
Qbeam is probably still the best. They have some at Walmart that are rechargable. I expect the sporting goods stores carry them, too. Cabelas, Bass Pro, etc. Check Sportsman's Guide, too, for a closeout special.