Best Buy has a student internship program for ages 16 and up to work in their stores. There are specialty positions for minors. You would still have to follow the minor labor laws of your state if you are still in high school, check with your school's guidance counselor to find out the rules in your area so you know what hours you can legally work.
Best Buy, like other national retail stores, are required to follow state and federally mandated employment laws. In general, the minimum age to work at most retail establishments will be 16 years old.