The relay should already be there!
it wasn't on my non-foglight car, you doof!
the wires are behind / under the front bumper... prolly wrapped up with the headlight wiring harness
if in the patently unlikely event you don't have the relay, I think it's #61.31-1374631 -- $14 at the dealer...
(but I will sell you the one out of Denis' car for $2 shipped)

I would try to stick to OEM fogs... expensive new, but if you are willing to be a little patient, you can buy one good one at a time (junk cars rarely have two good fogs), sometimes for less than the cost of a used pair.