<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
            DataSourceID="ObjectDataSource">
            <Columns>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:Label ID="AMOUNT_LBL" runat="server" 
                        Text='<%# "javascript:" + (Convert.ToInt32(Eval("id")) > 3 ? string.Format("{0:N2}", Eval("id")) : Eval("descrizione")) %>'
                        />
                    </ItemTemplate>
                </asp:TemplateField> 
...