DC is home to many souvenir stands and storefronts all trying to sell you the exact same merchandise. However, some places will sell you that merchandise for a significantly cheaper price than others. As a general rule of thumb; DO NOT BUY FROM THE FIRST PLACE YOU VISIT! Price shop! I have seen some stores selling hoodies for $60 and others selling the exact same hoodie for $25. Be smart with your money; you or someone you know worked very hard for it.
