The popular Logitech MX Anywhere 2 Bluetooth Mouse is down to $30 (Reg. $50) - 9to5Toys
Amazon.com: Logitech MX Anywhere 2 Wireless Mobile Mouse – Track on Any Surface, Bluetooth or USB Connection, Easy-Switch up to 3 Devices, Hyper-fast Scrolling : Electronics
Logitech MX Anywhere 2 review: A high-performance mouse for mobile users - CNET
Logitech MX Anywhere 2S Review: A Pocketable Mouse