I've also investigated this quite deeply. As I'm sure most of us know, the main problems with 'webcams', either the built-in ones or USB ones that you perch on top of your monitor, are the lens size, and the CCD/CMOS image sensor size. Manufacturers spouting specs like '4k' are deliberately misleading the public if the sensor and/or the lens aren't also upgraded.
The only cost-viable methods to get 'broadcast quality' imagery for streaming/recording right now is to buy a second hand DLSR or mirrorless camera that has 'clean' HDMI out that works without the camera auto-shutting down after X amount of time. There are a few sites out there that list the preferable models[1]. I've got a couple of old Canon DSLRs (That don't do clean HDMI) and a load of lenses, so I've been watching Ebay for a newer model Canon DSLR that I can afford. The lowest cost Canon DSLR body I've seen with unrestricted clean HDMI or that can take the Magic Lantern[2] firmware is about £150.
However... You also need a HDMI-to-USB dongle. This converts the cameras HDMI output into a standard USB Webcam input. I've already got an Elgato CamLink[3] (bought for a different reason a couple of years ago), but you can get cheap China knockoffs for about £15, I don't know how good they are though. My Camlink cost WAY more than that, so I have my doubts about the knockoff quality.
Finally, you need good audio capture that importantly is in sync with the picture. The HDMI to USB conversion adds a tiny delay to the image which can put your audio out of sync if you are using a standard USB microphone. Good software like OBS[4] can correct for this though.
---
[1] https://www.elgato.com/en/gaming/cam-link/camera-check
[2] https://magiclantern.fm/
[3] https://www.elgato.com/en/gaming/cam-link-4k
[4] https://obsproject.com/
The only cost-viable methods to get 'broadcast quality' imagery for streaming/recording right now is to buy a second hand DLSR or mirrorless camera that has 'clean' HDMI out that works without the camera auto-shutting down after X amount of time. There are a few sites out there that list the preferable models[1]. I've got a couple of old Canon DSLRs (That don't do clean HDMI) and a load of lenses, so I've been watching Ebay for a newer model Canon DSLR that I can afford. The lowest cost Canon DSLR body I've seen with unrestricted clean HDMI or that can take the Magic Lantern[2] firmware is about £150.
However... You also need a HDMI-to-USB dongle. This converts the cameras HDMI output into a standard USB Webcam input. I've already got an Elgato CamLink[3] (bought for a different reason a couple of years ago), but you can get cheap China knockoffs for about £15, I don't know how good they are though. My Camlink cost WAY more than that, so I have my doubts about the knockoff quality.
Finally, you need good audio capture that importantly is in sync with the picture. The HDMI to USB conversion adds a tiny delay to the image which can put your audio out of sync if you are using a standard USB microphone. Good software like OBS[4] can correct for this though.
---
[1] https://www.elgato.com/en/gaming/cam-link/camera-check
[2] https://magiclantern.fm/
[3] https://www.elgato.com/en/gaming/cam-link-4k
[4] https://obsproject.com/