Update: The coupon is gone now, unfortunately.
Through some combination of Bluetooth and I assume blood magic, 8Bitdo’s Nintendo Switch dongle lets you use pretty much any Bluetooth-enabled gamepad from your other consoles with a Nintendo Switch, a PC, a Mac, or even a Raspberry Pi. Hell, even the DualShock 4's motion and rumble features will work when you use this to pair it to a Switch.
It’s a bargain at its usual $20, and it doesn’t really go on sale, but Amazon’s offering a 5% coupon today that will save you a buck. That’s the best deal we’ve seen, and it’s a lot cheaper than buying a Switch Pro controller, if you already have some Xbox One or PS4 gamepads lying around.