Amazon offers Prime members the Logitech M705 Wireless Laser Mouse, model no. 910-001935, for $19.49 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.49.) That's a buck under our December mention and the lowest total price we could find by $5, outside of the deal below. It features a nano-receiver, eight buttons, 1,000 dpi tracking, purports to have up to a 3-year battery life, and requires two AA batteries (included).
A close price: Best Buy via eBay charges $19.99 with free shipping.