As one of its daily deals, Amazon offers Prime members the Logitech M557 Bluetooth Mouse, model no. 910-003971, for $20.75 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $8.15.) That's a buck under our August mention and the lowest total price we've seen (It's a current low by $5.) This wireless mouse features customizable buttons, vertical and horizontal scroll wheel, optical sensor, and ambidextrous design. Two AA batteries are included. Deal ends today.