I would buy lots of salt, travel to 1561 (Inka-Gold Rush) sell all the salt and buy gold for it. I would then sink the gold into a deep trench and retrieve it back in 2011.
Take the knowledge people know now to make back in the early 1900s, such as entertainment, weaponry, and computer technology to become the richest person ever in history. ( And also to make sure America would've been the strongest country ever with the weaponry part )