Probably somewhere in the range of $50-$200 depending on whether he’s be principal driver or occasional driver. Also, in NY drivers are entitled to the credit until they turn 21, I’m not sure how it works in NJ. your insurance agent could probably do a quote with and without the driving school credit to give you a better figure. Even if the insurance credit isn’t enough to pay for the school, he’ll get a lot out of it and be a better driver as a result, so it’s good for him to go.