HELP COLORED CONTACTS!?

ok so i want to buy colored contacts but im only 14 so i dunno if u need 2 be 18 :/ and second is where the heck can i buy some!? i live in scottsdale az im going to fasion square mall to look but im not sure if and whered they hame em plus ive heard u can buy them at walmart? and i need no prescription obviously and if anyone knows how much around about they might cost? thanks i hope you can help!