Newegg offers the refurbished Logitech MX Wireless Mouse, model no. 910-002896, for $24.99 with free shipping. That's $3 under our January mention and $15 under the lowest total price we could find for a new model. It features dual side buttons, laser tracking, and a Logitech unifying receiver. Deal ends March 17.
Note that Newegg lists both a 90-day and 3-year warranty; it's unclear which is correct, and it's unclear who backs it.