The Logitech MK270 Wireless Keyboard and Mouse set was just twelve dollars and fifty cents!
It's sometimes $16.99 or even a bit more, but that's still pretty damned cheap.
I expected it to be about as bad as the Amazon Basics Keyboard, which is the same price, but wired, and you don't get a mouse. You know those nasty squidgy roll-up rubber portable keyboards? Imagine one of those in a rigid plastic case, and you have the Amazon Basics Keyboard.
This, though, is a perfectly decent full-size rubber-dome keyboard, as good as most of the tat in, say, a Best Buy or Staples. The special keys worked, including a calculator key that actually brings up the system calculator. Fucking witchcraft!
It uses a tiny USB dongle, not Bluetooth, which means it actually works without hassle. It even comes with batteries, already installed, with little plastic slips you whip out to connect the terminals.
The mouse is OK too, though small and freakishly fast-tracking–a problem easily fixed in system settings. The scroll-wheel spins nicely, with soft, slightly tactile rotation, but is too stiff when clicking.
Why is this set so cheap? Even the unbranded junk with cheesy typefaces on the key legends isn't this cheap, and it's nowhere near as good. Something weird's going on. If you want a cheap wireless keyboard and mouse, get this one while it's going.