Here is an example that uses the coinmarketcap API, updating the price every 5 minutes. You can modify the code to put the text wherever you want, as long as you keep the id.
Save the code as demo.html and open it with your browser to see it in action.
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script type="text/javascript">
function updatePrice() {
$.getJSON("http://whateverorigin.org/get?url=" + encodeURIComponent("http://coinmarketcap-nexuist.rhcloud.com/api/btc") + "&callback=?", function(data) {
$("#BTCPrice").append("<center>BTC: $" + data['contents']['price']['usd'] + "</center>")
})
}
$(document).ready(setInterval(updatePrice(), 300000))
</script>
<div id="BTCPrice" style="height:40px;margin:auto;position:absolute;top:-20;left:0;bottom:0;right:0" />
My address is 14pZ8o1ASSCC7HqjJPU4UFXq9FrewW5GDc.