Well, their fully built race-application Advance Design coilovers run about $2k a set. With Koni innards it should be significantly cheaper, because you're not limited to SVX-fitment Koni inserts. They would use standard motorsport Koni valving in their housing, built to whatever spec you would like.

I'm guessing it would be a $1200-1500 deal, including the fabrication, the dampers, the springs, the collars, and everything. That's a guess, let me emphasize.