"36 or top score" would be for the ACT not SAT.
If you aren't looking for an increase, and you aren't looking for for your DS to get into a top school- you can find "tips and guidance all over the internet and prep books. My suggestion would be for him to self study. It would save you some money. With that said, I have not heard of SAT Wizard, but you can find some good SAT tutors on Wyzant for a reasonable price who will tutor online. Good Luck!