Would Best Buy Let Me Buy An R Rated Film

FYE gold, gold "any place That sells movies. I'm 15, & the movie is Sweeney Todd: The Demon Barber of Fleet Street. I'm not gonna 'rent it, I want to buy it. I've saved up money for it, and I Know That My local FYE has it (Unfortunatley That Was the Day I forgot my wallet) Would I Be Able to buy it myself or I Would Have to Have to Have an adult walk-in closet With me? Or Would I Have to Have an adult buy it for me?