Of Lights, And Not Lights

I tend to turn off the headlights when there aren't any cars around, to save the battery, but lately the cagers have been sneaking up on me.  I ALWAYS have the BIG STROBE going, you would think that would be enough, since I can SEE the halo it casts around me on the ground, and the flash off the buildings beside the road. 

But, I guess it is not.  I had a near thing yesterday on Jackson Drive with a car coming from a stop sign on the left.  I stopped right in front of them and POINTED the the BIG STROBE.

At any rate, has anyone seen a twelve volt powered flashing LED unit I could inexpensively add to the system? I've seen the nifty Planet Bike headlamps, but they have their own batteries, and I'm trying to stay away from MORE batteries.