Computer desks are catching dust all the time. So of course to have the idea of integrating a vacuum cleaner inside a mouse are just a couple magic mushrooms away.
With a push of a button the motor inside the mouse starts up and the sucking in of dust can begin. A small dust compartment inside the mouse needs to be emptied regularly.
The price is 1,980 Yen (~$20).
Via the Thanko CleanerMouse product page. (Japanese).