If you are considering setting up and installing a personal security system by yourself, the amount of setup involved can be daunting. Even if you do have the technical know how to get the wires plugged in correctly, the base station installed, scheduled, and connected to the internet properly; you still have to deal with the headache of actually running the wires and the ability to overcome wire length limitations.
Fortunately technology has come a long ways, and it is now possible to purchase a nice do-it-yourself home system for fairly cheap. Several companies have come out with IP based cameras which can connect to your existing computer network making setup costs much lower. However, unless you get the cameras on sale, they will end up costing as much as a traditional system. The brand I have gone with is D-Link. The D-Link DCS-930L and DCS-932L cameras are great; the 932 has night vision while the 930 model does not. When on sale you can get the DCS-930L for as low as $30 from newegg.com, and the DCS-932L for as low as $40.
The two reasons I chose the method I did for a personal security system are: it is easily implemented on top of my existing IP based network, and two it is very scalable. So I can slowly buy one camera at a time and increase my system as desired, needed, or money is available.
There are of course other security devices such as the magnetic open window detectors, but most security firms have long since stopped using those due to the inherent flaw that you can just break the window and they won't go off. Motion detection, night vision, heat sensing, and image capture seem to be the key features common to most modern systems.
Considering the price, these cameras have a wide range of abilities. Everything from emailing on motion detection, to built-in remote viewing over the Internet. Of course you can also schedule the activation of night vision or motion detection as well as choose where in the viewing area motion will be checked for and at what sensitivity level.
The biggest downside to this system is the resolution, or picture quality. While it works great in a normal house or office building, it is not good enough for facial recognition at long distances.
Convenience and Security Risks
The cameras do have an incredibly convenient wireless feature which allows you to setup the security network with almost no effort so long as you are within range of a wireless router. Using this method does put your system at risk for an interference attack. Even something as innocent as a microwave can take down a cameras wireless signal if it is close enough. However, the chances of a normal residential house being broken into by someone with enough knowledge and skill to take advantage of that seems unlikely. And for businesses who need to be more careful the camera does come with a standard ethernet jack.
These cameras do require power in order to function. Which means that a backup generator, or battery backups would be required to overcome an attack where someone cuts the power to the location.
Most of this does require an active Internet connection to work as well, which of course is another potential security flaw should an intruder cut your Internet access. While a redundant Internet connection would be nice, most people building their own system do not want to spring for such an expensive recurring cost.
Fortunately D-Link gives away for free a very nice software package called D-ViewCam which brings the power of a traditional base station to this custom system. It allows for video recording on schedule, motion detection, or manually. It provides remote access to both the cameras and archived recordings, and has extensive logs built-in so you know about any network related issues or user actions that have affected your system.
EDIT: I have since moved to Mileston's XProtect Pro system, an amazing product.
D-Link is not the only option out there, it just happens to be my favorite. Brands such as Wansview offer cheaper cameras than D-Link, but reviews indicate they may not last as long and the management software does not feel as polished as the D-Link offerings.
If you are comfortable with running wires you could go the route of an ELEC system, which are incredibly inexpensive for what you get. Less convenience, more functionality. The ELEC brand is currently the cheapest closed circuit I am aware of; obviously cheapness carries all the normal risks of cheap hardware and software.
So far I have had very little success combining more than one brand for the near free price I like. None of the brands software supports other brands hardware. However there are a few third party options that give something in this area. Blue Iris seems to be a common favorite among the industry, but the interface was not clean enough for me to be interested in the learning curve, and it is not free. iSpy was my favorite, it has a bit more polish and supports anything and everything I could possibly want. Unfortunately iSpy does not have a reasonable remote or mobile offering, the best I could come up with for a mobile app to supplement iSpy is called IP Cam Viewer Lite. It was able to successfully connect to both my D-Link IP cameras, and my ELEC CCTV system; the downside was I had to give up a lot of the custom and extra functionality the brands own apps gave. It was a great mobile viewer that rivaled and sometimes surpassed the brands personal software's viewing capabilities, but not much more.
In conclusion, if your building requires the additional security of being up through a power failure, and being less susceptible to other types of direct security system compromises, I would recommend going with the more traditional closed circuit systems. However, if you are looking for something quick that will cover 90% of every day events with minimal hassle, setup, or costs, then the system I have built is probably exactly what you are looking for.