Free: Contests & Raffles.
Never got the whole "ruin my night vision" thing. If you had night vision, you wouldn't need a light.
I run a cree t6 XML headlamp that uses the twin 18650 batteries commonly found in the modded nicotine vape boxes. The thing is brighter then any other headlamp I've ever seen. Maybe not the best for tracking on a blood trail, but works awesome for riding the bike in total darkness. Has multiple brightness settings ,focus, and a SOS function as well. These are a fraction of the cost of the big name lamps. The key is to toss the Chinese batteries that typically come with them and upgrade to true panasonic 18650s. Battery life is around 5 hours on brightest setting. Also nice to have a rechargeable unit that you don't have to spend a fortune on batteries.