固定金额，购买指定数量，2个梯度，（展示为批量加购按钮）

https://juan.sltestteam.shop/products/%E5%9B%BA%E5%AE%9A%E9%87%91%E9%A2%9D-%E8%B4%AD%E4%B9%B0%E6%8C%87%E5%AE%9A%E6%95%B0%E9%87%8F-2%E4%B8%AA%E6%A2%AF%E5%BA%A6-%E5%B1%95%E7%A4%BA%E4%B8%BA%E6%89%B9%E9%87%8F%E5%8A%A0%E8%B4%AD%E6%8C%89%E9%92%AE-