check your car for to see if you have the pig tails already installed. if not its not that hard to wire some in. ( I can tell you how to do it)
new headlight switch with the fog option... swtich out new for old
lower grilled that has a spot for fog lights..
What your going to want to do is acquire the following:
Lower grill for fogs. (get one used on here or try rock auto)
Fog light housings (got mine on rock auto for 10 bucks for both)
Headlight switch with fog option
Relay for the under hood fuse box. (it will go into the R13 slot)
Then just check your interior fuse panel and make sure theres a fuse there for the fogs.
If you want fog lights just for looks then by all means spend the money on some stock '00-'04 ZX3/ZTS fog lights. These fog lights don't light up crap, period. They can't even serve as daytime running lights either since you have to have your low beams on to run them (unless modified).
If you want a functional and OEM solution, the SVT Focus front bumper kit is your best bet. Unfortunately it's not cheap. But it does come with a sexy front bumper (unpainted), fog lights, horn, lip, and lower grille. The only other thing you'd have to buy is the light switch.
Additional modification was necessary on my old ZX3 because the fog lights on the SVT Focus model are out wider to the sides. I had a "Ford Genuine" body shop handle the painting and install of my bumper. They had to extend the wires for the fog lights a tiny bit to get everything hooked up properly.
My grand total bill (including purchase of parts) came out in the mid $800 range.
Bottom line, coming from a stock 2002 ZX3 with fog lights versus SVT Focus fog lights... there's NO mistaking that the SVT Focus comes with real, functional fog lights. I personally wouldn't waste my money on a set of ZTS/ZX3 fog lights. That's your call.
Here's what my Focus ended up looking like in the end. Totally worth it, IMO.