I've watched a lot of game streams, and I've streamed a bit myself. However, poor audio or video will make me stop watching a stream real fast. Razer has a couple products poised to prepare streamers for professional-grade productions: the Kiyo camera and the Seiren X microphone.
Most people don't have good lighting setups near their computer for video recording, something that tends to result in blurry or otherwise poor-quality streams. The Kiyo purports to bypass this problem with its built-in lighting. Razer says that the twelve configurable brightness levels on the Kiyo's LED lamp eliminate the need for low-light compensation modes in the camera. The Kiyo can record or stream in 1280x720 at up to 60 FPS, or in 1920x1080 at up to 30 FPS. The camera can be used sitting on a desk or attached to a monitor.
The Kiyo includes an omnidirectional microphone, but there are better options if you're serious about audio quality. Instead, you can pick up a device like the Razer Seiren X, a USB desktop condenser microphone with a shock-absorbing mount to filter out your keyboard mashing. The Seiren X's signal-to-noise ratio is 85 dB. The microphone's super-cardioid sensitivity pattern is fairly tight, too, meaning there's a relatively narrow angle from which it can pick up unwanted noise. Although Razer doesn't list the Seiren X's exact size, judging from the pictures, its base is about as wide as a mouse. The fairly compact dimensions should make it easy to place and use on a desk.
Razer has the Kiyo camera and Seiren X microphone up for sale on its web shop, although the Kiyo is currently showing as out of stock. Either device will run you $100. The company says the products will hit other shops and physical stores at the beginning of next year.