As one of its daily deals, Amazon offers Prime members the Logitech M557 Bluetooth Mouse for Windows and Mac, model no. 910-003971, for $21.99 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $8.15.) That's the lowest total price we could find by $8. This wireless mouse features customizable buttons, vertical and horizontal scroll wheel, optical sensor, and ambidextrous design. Two AA batteries are included. Deal ends today.