For under $40, CatEye Volt 400 should do the trick. It has replaceable rechargeable cartridge battery so after a few years when the battery doesn't hold a charge anymore, you need only to replace the battery instead of the whole light, and you can carry a spare battery for those long, long ride.
Modes and run time are (taken from their website):
High mode 400 lumens：3hrs
Middle mode 100 lumens：8hrs
Low mode 50 lumens：18hrs
Hyper Constant mode 400/50 lumens：11hrs
Flashing mode 50 lumens： 60hrs

On CatEye website, you can compare the light intensity of their differently light and see what best suite your need.