Have you considered aftermarket like Hella or PIAA? New good-quality aftermarket lights will probably still be cheaper than used OEM, and the light output will be better. That's what I did with mine, and I sold my OEMs for a tidy profit. Just a thought.
^^Careful. The link above is for the driving light version of the 500s, which I agree are awesome, but I don't want to confuse the OP, who asked for foglights.
To the OP: Garrett's link is for driving lights, which are higher powered than the high beams. The fog light location isn't the best for them, but they'll still work great and look stock. They are ONLY for use when you would use your highbeams, though. They will blind oncoming traffic more than your highbeams.
Hella makes a fog light version of the 500 which is virtually identical, but has a fog beam pattern. These will function the same as the stock lights, but the output and beam spread is much better than your OEM foglights (this is coming from experience as these are the lights I have).
The kartboy brackets will adapt the 500 mounting bolt to the stock bolt locations (in the corners). You will need to drill out the plastic and metal bracket directly behind the light in order for the mounting stud on the 500's to clear, but it isn't difficult, and is invisible once the lights are installed.
I reused the stock wiring, so I just installed OEM connectors I picked up from the dealer to the 500's. This makes them totally plug and play into the stock wiring, no cutting required. Since they are the same wattage as stock, it's the same electrical load as your OEM lights, so no dangers over melting your wiring or anything terrible like that.