I installed the front camera ($20 cheap one, that I had on old car) for now. But, I am going to replace it with front/back camera with parking recording (Blackvue DR490-2CH) as requested by my boss (wife). I ordered one from
BlackboxMyCar Canada | Dash Cam Experts | Car Camera | Dash Cam Store and they seem to have good price on refurbished version.
The wiring is not too difficult to do. There are several videos available on YouTube for the reference. It took me around 30 mins to do. The next one (front/back) will take a bit longer as I will need to wire to rear window. I'm planning to install the rear camera after getting my Model 3 serviced and window-tinted.