$(document).ready(function(){      
    function animUp() {
        $("#top-buyNow").animate({ top: "1px" }, "slow", "swing", animDown);
    }
    function animDown() {
        $("#top-buyNow").animate({ top: "6px" }, "slow", "swing", animUp);
    }
    $(document).ready(function() {
        animUp();
    });
});