Consider a Streamlight. The TL-2 fits your criteria and at about $40, you cn get two. The xenon bulb cranks out 114 lumens.

Or you could go with the TL-3 for 211 lumens for $50-60.

The bright lights will probably buy you the time it takes your asailant to look away and reaquire you. Time to cut and run, and if you are fast enough, to get away. Definitely time enough to close and engage. If you are too far away to close, the light probably shouldn't come into play.