Has Anybody added a Vent Fan w/No 12v connection?

I wired a fan upgrade for our front vent by pushing a coat hanger fish wire through the foam insulation between the ceiling and roof from a nearby light fixture to an A/C duct, and then from the duct to the vent opening. Once the fish wire was pushed through, it was used to pull the wires through of course. The closest light fixture to the vent is wall switch controlled, so I had to get the power from a fixture a bit further away that was direct wired with an internal switch.