Go directly to the shopping cart

Hi,

is there a way to have a link which adds an item to the shopping cart and proceeds with checkout right away?

As an example I have a pricing page http://www.visiongolden.com/pricing/ where you get to choose the product. As of now, when you choose one of the options you get to the product page. And then you have to click "buy now" again, which is not convenient.

Is there a way to proceed directly with checkout?

Thanks for advice!