Just cost him the regular price plus what he owes you. If he asks about the price tell him that he owed you money from seven years ago, and that if he wants to continue doing buisness with you that he better pay up. You don't have to sink yourself down to his level and rip him off. Be the man with balls and confront him, and give him the option. If he refuses to pay up don't get pissed about it and start a fight. 30 bucks isn't worth a fight.

Think of it this way..... for 30 bucks he's out of your life forever, and you're never going to have to loan him money or deal with him again.

Karma is real.