This Chromebook wireless keyboard combo is less than $50 - 9to5Google
Amazon.com: Logitech K380 + M355 Wireless Keyboard and Mouse Combo-Slim portable design, quiet clicks, long battery life, Bluetooth connectivity, multi device with Easy-Switch for Mac, Chrome OS, Windows-Graphite : Electronics
Logitech K580 for Chrome OS + M355 | Keyboard & Mouse Combo
Use a standard PC keyboard with your Chromebook - Chromebook Review
Amazon.com: Logitech K380 Multi-Device Bluetooth Keyboard – Windows, Mac, Chrome OS, Android, iPad, iPhone, Apple TV Compatible – with Flow Cross-Computer Control and Easy-Switch up to 3 Devices – Dark Grey :