If you’re interest in night MTB riding, but don’t want to shell out hundreds for HID lights, here’s a suggestion that works great for about $30.
Sams Club sells a two pack of LED flashlights. They’re 3 watts, 20 hours steady runtime on 3 AAA batteries, and focus from spot to flood. Strap them onto your helmet, and you’ll have plenty of light for some post-sundown singletrack!