Amazon offers the Logitech MX Master 2S Wireless Mouse in Graphite for $79.99 with free shipping. (Office Depot and Office Max offers it for the same price.) That's the lowest price we could find by $5. It features up to 70 days of power on a single charge and a unifying receiver for use with up to three devices.

Note: This item will be in stock on January 6.

Update: The price has increased at Amazon; however, Office Depot and Office Max still offer it for $79.99 with free shipping.