My DS11 is a 2nd degree black belt in Tae Kwon Do, almost a 3rd degree. He has been going to the same school since he was 4, but he took a year off when he was 5. We pay about $1,000 a year for his lessons, but the school he attends lets him take classes at anytime on anyday, plus he is on the Demonstration Team.
Make sure you look for a good school and you like the philosophy of the owner. Our owner is a 9th degree Black belt fom Korea. His school has been in our area for many many years. He has former students whose grandkids are now attending the school.
Ask for recommendations from other parents and go and look at the schools when class is in sessions. Most schools will offer lessons for a month or several weeks at a reduced rate. That way your DS can try it out and see if he likes it. Check out the schedule of classes. Some schools only teach a certain belt level on a certain day, so as your child moves up in rank, you have to switch times and days. If you are interested in TKD look to see if they are affliated with the United States Tae Kwon Do Union (USTU)and the Master instructor is certified by Kukkiwon. Our Black Belts get a certificate from Kukkiwon in Korea stating that they are certified Black Belts.
My son loves TKD and it has helped him so much. I know that he can defend himself he he needs to, he has gained self-confidence and he has been taught to try to resolve your conflicts with words before fighting. The friends he has made at this school have been wonderful. He has known most of them since he was 4, they have all moved up in rank together. They have a lot of fun going to competions together and even competing against each other. They are all so supportive.
here are a few links that can give you some more information. The first is to my son's school. The second is the USTU and the third is a little information about Kukkiwon from some guys website.
H.K. Lee's TKD school
USTU
Kukkiwon Information