@Jubee
I've had somewhat recent experience with 3 types of systems
1. Generic HHD based DVR with hard wired co-ax and/or IP (but I prefer IP) cameras
Most run on HikVision software. It is great, powerful software but you really need to know networking to make it work. Remote access direct to DVR through a Static IP. I set them up on their own VLAN separate from the normal home internet network.
I bought at one of the electronic stores beside Denny's and the Dixie and 401 incall hotspot! Pretty good support.
You can get them on amazon too but you have to be the one to install and administer them. Or else you will become your buddy's 24/7 Tech Dept. The documentation is not great and there is no real support for amachers.
These are cheap semi-kijiji guy pro-level systems.
2. Various wifi D-Link type $99 security cams. Wifi and wired IP in the same cam. Pretty good quality and you don't need any subscription.
3. Amazon Blink cams. I am actually really impressed with the system. Simple, reliable, good features and video quality. Full line of indoor, outdoor and doorbell units. All reliable and the outdoor unit lithium AA's were still strong every year I replaced hemm in the Fall. Were up north and worked down to -40C . Best of all, the app is super easy to configure and use.
Only downside is that some features are crippled unless you pay $10 a month for the subscription. And I only say downside is because of the gerneal entitlement of the public that all online services should be free. Or else it is a "rip off".
So in the end, unless your buddy has complex security needs, the Amazon Blink system seems like a good fit.