Stick with the wal mart fog light add two toggle switches and a Sealed lead battery and you have a golden setup for roughly $50 provided you have the tools.
I use 20 w x2 with two switches to control high and low beams.
My battery is a 5 amp hour that ways a ton i swear
If I am right I can run these lights both beams for 2 hours. I am not a math wiz so feel free to correct me on my run time. I love this set up. I want to upgrade battery to something smaller that will give me the same run time. But I am one cheap broke kind of guy. I will post pics of my setup when I can.