Amazon.com: Twelve South MagicBridge | Connects Apple Magic Trackpad 2 to Apple Magic Keyboard Allowing Them to be one Unit for Desk or Lap use - Trackpad and Keyboard not Included : Electronics
Logitech's Illuminated Keyboard has a built-in trackpad at $60 (20% off), more from $18
Wireless Keyboard Touchpad Not Working (Troubleshooting Guide)