Newegg offers the refurbished Logitech MX Wireless Mouse, model no. 910-002896, for $27.99 with free shipping. That's $17 under the lowest total price we could find for a new model, although we saw a refurbished unit for $3 less last week. It features dual side buttons, laser tracking, and a Logitech unifying receiver.

A warranty applies, but it's unclear who backs it.