Search ebay for Ultrafire, basically Chinese clones of Surefire. Can get them extremely bright, the majority run off CR123a batteries (best bought in bulk off ebay) you can get rechargeable ones but in my experience they are not fantastic, they give slightly more voltage but they don't last as long.
I have personally used Ultrafire for 6 or so years, all of them have been fantastic to be honest and at sub £20 you can't really go wrong.