The current Focus bodykit is not widely available, as it is very costly (it not only has front, side, and rear mouldings, but also multiple peice rear wing and side flares, plus pumped guards). The rear wing also has defect issues as to the amount it restricts the vision out of the rear of the car. You would then also need to buy different wheels for the offset, as the guards are now an extra two inches wider.
Economically, it's a nightmare, it would cost a considerable amount of money for all the peices and new wheels, and even more because you would have to get it custom made. Or ordered from the Team RS factory in Europe (mortage your house for this option).
I can tell ya coz I looked into this myself when I first got my Focus.