I think decently bright lights start at the 10w halogen level. One way to get a reasonably priced one is to keep checking web sites like Nashbar and Performance. From time to time, they'll have a good one with a long-lasting reasonably-sized battery (usually and NiMH) for about $80.
Edit: As I explain in this thread, my Cygolite died after about 18 months of use. The company wants $100 to $200 to replace the lamp and/or ballast. That's a rip-off.
For example, the
CygoLite Nitro XM Headlight is now on sale at that price
at Performance. I have a Cygolite HID, and it works great. A rubber gasket wore out and the company sent another for free. That's just an example. You'll probably find similar lights on sale again at those sites.
The main types of batteries are:
Li-ion
NiMH
NiCad
SLA (lead acid)
As you go down that list, the batteries get heavier, have shorter run times, but also get cheaper.
Also pay attention to the chargers. "Smart chargers" will turn off automatically when the battery is fully charged, which can prolong your battery life. Some chargers also work more quickly than others.
Of course, the Total Geekiness people can MacGyver a brighter light for less money. They also will attach timers to their dumb charges to approximate what a smart charger does. Whatever you do, don't give up the LED you have. Keep that as backup for the times when your main battery runs out in the middle of your ride.
Edit: One final piece of advice. A light is a basic piece of safety equipment for night riding. So, if you are going to be riding a lot at night, buy the brightest, longest-lasting light you can afford.