YE.onDOMReady(AddItemsToBuyButton);

function AddItemsToBuyButton()
{
    var buyButton = YAHOO.widget.Button.getButton("buyButton");
    if (buyButton)
    {
        var newBuyItem = { text: "View Catalog", url: "http://www.smugmug.com/help", target: "_blank"};
        buyButton.getMenu().addItem(newBuyItem);
    }
}