I'm really impressed with the Lezyne self-contained LED lights. You can buy the Super Drive, which puts out close to 500 lumens on high, for about $100 on line right now. Lezyne is coming out with new models, so that's why the prices are low. If you don't mind paying more, it might be worth paying extra for the new models. What I like about the Lezyne lights is that they use standard 18650 rechargeable batteries, so you can carry spares to extend run times. I've got a Light & Motion Urban 500, which is very comparable to the Lezyne in terms of light output, but it uses a proprietary battery so it has to be recharged when the battery gets low (which takes several hours) rather than simply popping in a different battery.

If you want to get about the same light output for less money, look into LED flashlights. You can find a number of good quality flashlights in the $20-30 range that will put out 300-600 lumens with decent run times using 18650 batteries. You would also need to buy a handlebar mount as well as a charging unit and spare batteries, but that option should still come out cheaper than the various self-contained units.