World Cup Soccer is a very good pin and quite popular among the collectors. Expect to pay $1700-$2000-ish for a nice, fully working one. A minty one will probably command a lot more and one that needs work could sell for less.
If that's outside of his budget, Gottlieb made a soccer themed electromechanical pin called "Soccer". One of these could be picked up for $500 to $600 for a decent looking, fully working example. I've got one myself and it's a solid playing pin, I rather enjoy it. EM's can be a little fussy at times, but properly serviced can be quite reliable. They generally have a slower, more relaxed gameplay then something like World cup Soccer (or most any digital pin for that matter), but cleaned, waxed, fresh rubbers and properly setup can be just as fun to play.
Regards,
D