Why are we a dealer for Lupine lights costing from $335 and up when you can buy a "5000" lumen light (Image 5000 Lumen Bike Light Review) on Amazon for under $25? Well, risk of fire might be one of those considerations. Check out the effects of a bike light lithium battery fire (with pictures): http://www.singletracks.com/blog/mtb-interviews/a-cheap-chinese-bike-light-nearly-burned-down-this-riders-house/
Lithium holds a lot of potential energy which gets released as heat and hydrogen. Remember that high school chemistry demo when your teacher dropped lithium into water to get a nice explosion to happen. If you don't, here's a YouTube video of what happens so you don't hurt yourself: https://youtu.be/zoukoY_DAwY Yeah, that's the amount of energy stored in a little AA lithium battery. Imagine how big of an explosion you can get with a battery that can run a 1500 lumen light for 2 hours.
This next guy is a contender for the Darwin Awards. This YouTube video shows what happens when he overcharges a lithium battery as might accidentally happen with a cheap light's overcharge protection circuitry: https://youtu.be/SMy2_qNO2Y0?t=5m30s
What you're paying for with a more expensive light is the quality of the battery and the charger. The LEDs themselves now have become relatively inexpensive. I had purchased one of the original Chinese-made Magicshine lights which was recalled for batteries catching fire. I decided that saving 200 bucks wasn't worth the risk of my house burning down to the ground so I got a German-made Lupine Piko. The Lupine batteries still charge up to about 95% of full charge after 4 years of use.
A Magicshine still costs about $130: http://www.magicshineusa.com/products/lights/mj-872-magicshine-1600-lumen-bike-light
The Lupine is about $200 more, but that gets you a much higher quality charger and battery:: http://www.lupinenorthamerica.com/2016_piko_4_smartcore_helmet_light.asp
That's all for today, but for all of you pyros that liked watching the explosions, here's some more lithium battery explosions (These are professional pyros. Don't do this in your own home.):
Laptop Lithium Ion Battery Explosion. https://youtu.be/V482lvMRXUg?t=1m35s
Nail penetration testing of a Lithium Ion battery: https://youtu.be/f30fBFitkSM