Did anyone install CCTV to monitor their helper? How much? Where to buy? Any brand to recommend?

I installed Tyco/ ADT. They charge a monthly fee of $50 per month for 2 cameras with $10 additional per camera. Cameras are HD and Night/ Day. Free installation. It also comes with a free DVR that can hold up to 1 month of recording. And we have the app on our phone so we can view live and replay remotely. I thought they were quick and professional and great service. Our other option was to buy a D-link camera (aprox $200-250 per camera) but it needed Wifi for which we dont have great reception all over the house and would need us to either install ourselves or get a handyman. We preferred outsourcing it so it installed quickly and efficiently and would be maintained. And their giro payment facility makes it hassle free.