While I fully support your choice to shoot and your desire to own your own gun I would not sell anything to you without your parents consent. My son is 12 and he loves shooting. He is saving up his money to buy his own 22 rifle and his own 38 revolver. Once he has the money saved I will buy them for him to use and when he is legally old enough to own them they will be his. However, if someone sold something like that to him without my knowing I would be extremely upset.
I'm guessing from your need to find someone to sell you a gun and your avoidance of the questions related to your parents/guardians feelings on the situation that you in fact do not have their blessing. While there may not be a law prohibiting you owning a gun the fact is you are still a minor and someone else's responsibility.
I hope you get what you are looking for, be safe and enjoy the hobby!!