I am quite sure the OP will get a lot of options. But, if the OP wants go on the cheap, the above duo for less than $10 can't be beat. I have two of them, and the mounts. and they give off good light for my night time commute. I have stronger lights, and most of the time I am running the stronger one. One day I was in a hurry, these two had fresh 18650s in them, so I took off my 26650 lights, slapped them on, and o boy. The thrill was that each light/mount combo is under $10 So, two of them, plus one for the helmet, you rae out of $30.

Now, if you pockets are deep, go for one of the battery pack deals.. And always go with TWO up front. You got a back up or you can run them both at one time. Good for trails I think where you need searing light.