Microsoft Natural Ergonomic Keyboard 4000 for $24.99 shipped. To get free shipping, simply need to sign up for Staple’s rewards program, which is free and easy. Here is a screenshot for your reference. Alternatively, it is available at Amazon for $24.99 with free shipping on orders over $35. This keyboard features a 14-degree gable, 12-degree split and natural arc, along with 7-degree reverse slope for a more ergonomic design.