How much does birth control cost at a teen clinic?

Me and my boyfriend have been together for 3 years now and we have decided to have sex. We have talked about it and we want me to be on birth control. Problem is my parents don't approve of sex outside of marriage and i don't have a lot of money. I was wondering how much it would cost if i got birth control at the local teen clinic? My best friend told me that it is free but i just wanted to ask...