I got mine at the age of 15, I say got I mean borrowed the spare for my dog, and later bought one after walking to the nearest pet shop.
In all honesty? I'd say that if you do get one, because no one can stop you if you have the money to buy one, then to only wear it in your room. Also, make sure you have an explanation planned before you buy one. If you don't? Expect yourself to have an awkward conversation with your parents.