Google added two new ways to easily add Google Checkout as a payment option for items on your Google Sites pages. “To add the button right from your Sites page, look for Google Checkout "Buy Now" Button Gadget in Google Sites list of featured gadgets. Then setup your gadget with the item details and display settings in just a few clicks. To learn more about how to add gadget to your Sites pages through Google Sites, see this step-by-step instructional article. Alternatively, you can also generate the "Buy Now" Button in your Merchant Center and copy & paste generated button's code snippet into your Google Sites page HTML code. Just click the button while in your Google Sites edit page mode and Sites will automatically embed the button in a gadget for you,” says Google.