I would suggest there are three levels of choice – low cost imported systems the like of which you see in CPCs mailshots, conventional analogue systems with connectivity either by coax or by wifi and the more professional systems that are digital based and connect with CAT5 cabling.
The lower cost systems might just have one camera that can feed into your house TV.
The CAT5 systems carry the digital video data and the power over the CAT5 cable so it is an easy install with one connection. The base router accepts all the cables into it and provides a recording facility, local monitoring facility or a viewer via a smartphone wherever you are.
The analogue systems usually need a power source local to the camera and then bring the video back either on coax or wifi. They also have a base router, recorder and local monitor. Many of these also have remote monitoring on a smartphone.
Both analogue and digital systems will have some form of movement detection on areas that you define on each camera picture and with adjustable sensitivity. The digital cameras seem less prone to false alarms.
Have a look at COP-EU to get some ideas of what is professionally available but they do not show prices unless you are a registered dealer with them. Look at **LINK** which is a local supplier that I have used who does not seem to have an axe to grind and will give you a fair assessment of what you ought to go for.
No association with COP or QCCTV. Hopefully between the two you will get on the way to a solution.
I have an 8 camera digital system at home and it is very reassuring when we are on holiday to be able to see what is going on inside and outside the house and workshop via smartphone if only to see the sun shining at home and the rain pouring down where we are.
Alan