Logitech K750 Keyboard | $38 | Amazon
Graphic: Shep McAllister

Remember the little calculator you had in school that powered itself via a tiny solar panel? Logitech makes an entire wireless keyboard based on the same concept, and it’s on sale for $38 today, within a few bucks of an all-time low. Assuming you don’t live in a cave, you’ll never have to charge it.