I didnt use a professional installer for mine but installed the BlackVue 650 dual channel myself. It took several hours but wasn't really hard and I'm not very mechanical.
For power, many cars don't have it under the microphone cover. Its very easy to pop it off and check. If not you'll need power from someone else. Either the normal switched power from the 12V power port or hack something up in one of several ways. This is the one I used:
How to add a constant 12V power supply to your Model S | Tesla Living
If you think about doing it yourself, here's my notes from my own install:
Dual Channel Dash Cams for your Tesla | Tesla Living
I've had no problems since the install. Good luck with it either way.
One piece of advice is that you may want to turn off audio recording on it when you get it installed. There are various laws prohibiting audio recording of people without their permission.