Just had to replace the OEM switch for my Hondaline fog lamps. The backlighting will still work even when the switch burns out. If your switch still lights up, you have power to the switch. $40 for a new switch plug 15 minutes of your time and you'll have working lights again.
On my Big Bike fog lights I had an interment problem with them and it turned out to be the wiring harness that has the relay on it. Big Bike doesn't sell that part so I ended up getting one from Electrical Connections. After the part arrived I figured out that one of the connectors inside the plug had never been "seated" properly.