Grantcoin can be traded for Bitcoin and U.S. Dollars on SouthXchange (English and Spanish interface):
If you want to trade the GRT/BTC market, you will need a separate way to exchange Bitcoin for your local currency. Reputable and user-friendly places to buy and sell Bitcoin online include Coinbase (U.S. Dollars) and Bitstamp (U.S. Dollars and Euros).
If you would like to make a large purchase of Grantcoin — $250 USD or more (or equivalent in another currency) — and you don’t want to move the market price through your own buying activity, please contact the Grantcoin Foundation to discuss making an off-market purchase from our currency reserve.