I use one. I got a whole set up on "the auction place" for about $300. Camera ,lipstick cam, external mic, batteries.
It is a little bulky to carry, so you have to plan for it. I made a camera holder for the front of my chest protector. Some put the camera in a camelback or a fannypack.
I'd check "E" bay occasionally for a complete setup or buy the external cam and get a used recording camera (with video input).