buy gold

Can someone direct me where to buy gold in the US? My aunt is looking on investing in gold and silver and has commissioned me to find me the best stores or outlets where she can purchase some. She is convinced that the beauty of a gold bar lies in its proven ability to diversify investments, protect wealth and preserve one’s purchasing power. She has been constantly communicating with me on updates as to where she can buy them but as of yet, I haven't given her any recommendation whatsoever. Not being familiar with the US is one of my greatest challenges so far so I am seeking the help of all my US based friends to recommend some stores for me. I would really love to help my aunt but I am as clueless as her. Yay!