I know some people get it at their dealer (its a rip like anywhere from 12-24)
I've heard people get it at autozone, I personally got mine from Pepboys. Those are around $4.99 (what i paid and what others have at similar type stores)
Well never went for a S, but my original 6i auto - everything else standard, came in at $14,700...so I have no idea if that gives you an idea...
This was about a year + or so..2005 model.