The Light & Motion Urban 350 is down to around $30-35 now. Hard to beat that value with any farm rigged flashlight and mount.

Even better, for folks who need more runtime per charge. the upgraded L&M Urban 500 is now available in a Rando version with double the runtime over the original: 3 hours on high, 6 on medium, 12 on low and a full day or longer on pulse. About $65 on Amazon.

No need to fuss with extra batteries -- which I've done with my Serfas SL-255, which uses a pair of AA batteries. That light isn't a bad value for $20 or less, which includes an excellent mount. Maximum output is 255 lumens, adequate for some purposes. Main problem is the narrow beam, which I actually prefer for the MUP at night to avoid blinding oncoming cyclists and pedestrians. But it's a bit narrow for rural rides. I might buy another if the price drops to the lowest I've seen, around $14.