Probably around $50. But the plastic housing of NO bulbs may melt with PC's because PC's get hotter than NO bulbs. You will need to install a fan to keep it cool and prevent the melting.
It all depends on the set up. One 28w or 55w PC bulb is going to cost you $25-$30 delivered to your door. If your setup has 2 bulbs then you are already looking at $50.