Check out PushX3 write-up on Fitness Gizmos titled, “PushX3: Push Up Device”: http://www.fitnessgizmos.com/pushx3-push-up-device/
Here’s an excerpt:
Meet the PushX3: a compact, versatile push up device that helps you push your body in a whole new way. It is designed to help you build strength in your core and upper body using stability forces. The device is lightweight and easy to take around. You can easily integrate it into your existing workout routine to keep your body on its toes.
PushX3 enhances traditional push-ups, allowing you to push your body harder. Sets you back under $30 at this time.