Example:
$500 =
Just enter these lines of code where you want the prices to be:
[img]http://btc-priceimg.herokuapp.com/img/500[/img]
[img]http://btc-priceimg.herokuapp.com/img/450[/img]
Script courtesy of http://btc-priceimg.herokuapp.com/ - donate to him if you hate me. Or use preev.com if you want to torture your customers with a script that wildly fluctuates spot prices, which is exactly what an average calculator SHOULDN'T do.