Logitech makes some of the best webcams around, and the C270 has served as the company's entry-level webcam since 2011. The C270 can always be found for a low price, but today it's even lower: just $9.99. For context, the usual price on Amazon is $19.
The Logitech C270 is a no-frills 720p webcam, with a built-in noise filter for clear microphone audio (as clear as you can get from a webcam, anyway). Since it has been around for so long, it works with all operating systems, including Windows, macOS, and even Linux.
While this webcam doesn't have the 1080p sharpness of the Logitech C920 and other high-end models, it still works great for Skype, Discord, and other basic use.