script.gs

//https://coinmarketcap.com/api/
//https://blockchain.info/ticker

function getReal() {
  return getBitcoinBrl() / getBitcoinUsd();
}

function getBitcoinBrl() {
  return getValue("bitcoin", "BRL");
}

function getBitcoinUsd() {
  return getValue("bitcoin", "USD");
}

function getEthereumBrl() {
  return getValue("ethereum", "BRL");
}

function getEthereumUsd() {
  return getValue("ethereum", "USD");
}

function getValue(coin, convert) {
  var url = 'https://api.coinmarketcap.com/v1/ticker/' + coin + '/?convert=BRL';
  var response = UrlFetchApp.fetch(url);
  var json = response.getContentText();
  var data = JSON.parse(json);
  var value = 0;
  if (convert == 'BRL') {
    value = data[0].price_brl;
  } else {
    value = data[0].price_usd;
  }
  Logger.log("Price " + coin + "/" + convert + ": " + value);
  return value;
}