Riding at night is a ball since I got a $30 light from dealextreme. At 900 lumens, it is pretty impressive:
http://www.dealextreme.com/details.dx/sku.12623
With 2 batteries and charger it is about $50.

I don't know that I trust their quality 100%, but I have a 50 lumen 'blackburn flea' on my helmet to use as a backup and when changing batteries. Takes several weeks to get the thing, but not too bad "for the money"

It is pretty nice having a light on my bike almost as bright as motorcycle light. People do think I am a motorcycle with this much light and when traveling over 20mph. Much better than a "blinky" light, as no one ever seems to expect me to be riding 20mph with a "blinky" light - its nice to have fewer people cut me off because they don't know I'm "just" on a bicycle.

If you are 100% dependant on the light, go for long rides, or in bad weather, you probably want something made in the USA with better quality. But its not worth $250 for me to get a hard core setup - $50 was more like it for me.

Below is a comparison of the flashlight to a standard H4 light you may find in a motorcycle or a car. Nope, it isn't as bright as an automotive light, but its getting close. Not bad for a bicycle.