Here's my favorite low-budget lighting system.
Flashlight ($16.70):
http://www.dealextreme.com/p/ultrafi...-1-18650-55241
18650 cells ($7.99 for two, gives you a spare)
http://www.dealextreme.com/p/trustfi...pack-blue-5790
Charger ($6.90)
http://www.dealextreme.com/p/digital...y-charger-6105
Handlebar mount ($2.20)
http://www.dealextreme.com/p/cycling...-holder-105213
$33.79 including shipping. It will take 3 weeks to arrive. I have a MagicShine 900, but honestly, this works just as well and if I were starting over, I'd get this plus a PDW Danger Zone and call it done. I've gotten other flashlights including more expensive ones that were not reliable, but this one has been solid for me. I don't have to run it on high regardless of whether I'm in town or out in the pitch black country going down potholed gravel roads, so I get more than the 50 minutes or so you'd expect to get on high with one cell. More like 90 minutes.
I might get a 2nd flashlight and keep the 2nd battery in it, just to have a full backup of everything when riding. for an extra $17 it seems worth it. I might even buy a 2nd mount and just keep the 2nd flashlight right on the bars so it would just be one button push if the first light went out.
This will blow away anything you can get from normal bike light suppliers for anything close to this price, and as a bonus it's a darn nice handheld flashlight, and it's totally waterproof.
Don't let the weird battery scare you off. They're cheap and the charger is cheap.