No matter what you decide to do, you need to make sure you actually have a system that will work the way you want it to.
A lot of companies today are selling a lot of systems with a touchscreen control panel, just a couple door sensors, a motion detector for hallways, and maybe a glass break sensor or two. That isn't even close to good enough, for most homes. ...and that's because the salesmen get bonuses/commissions based on how much of the allowable equipment cost they don't let you spend.
If you're worried about glass breakage, you need sensors on each glass pane (the crap the alarm companies sell you won't work through drapes, blinds, or any obstruction between the window and the sensor; they have a limited range; and most are prone to false alarms).
If you have windows that are likely points of entry by being pried open or having the locks drilled, you need a sensor on each of those, as well (possibly each pane).
Have expensive tools (or a lot of cheap tools) in a garage or shop? You'll want coverage there, too. Overhead door sensors, window sensors, man door sensors, motion sensors, glass break sensors, and smoke detectors should all be considered.
If you have a safe (or seven), you may want to consider putting sensors on the doors, or at least the door to that room.
Have pets that roam the house, or can come and go as they please? Make sure you get motion sensors that are capable of dealing with that.
You don't have to have an alarm company install the hardware. You can buy it and do it yourself, and then set up a contract for monitoring -- you just need to make sure, beforehand, that the company you intend to use for monitoring has a network and software compatible with your alarm system. Installation of most modern systems can be done in less than 3 hours. If you use surface-mount sensors, instead of hidden sensors, you could probably get an entire system installed in less than 1.5 hours.
I had a system installed and monitored by Vivint (formerly APX) for 3.5 years. I was satisfied with everything but the equipment costs, lack of warranty support, and contract length. The warranty support issue was not, necessarily, Vivint's problem (the sim card in my wireless transmitter fried), but they also flat-out refused to provide me with any information to try to get the manufacturer to cover replacement. Their customer service and support were great, the rest of the time; as well as the monitoring.
I'm currently planning and piecing together my next system. It will be owned outright, cost less than half what the alarm companies charge, be exactly what I need, and be installed by someone competent (me
).
Some internet searches for things "DIY home security", "DIY alarm system", and "home security forum" should get you started, if you want to learn more about possibly buying and installing the system yourself.
My planned (wireless) system, if you're curious, will be using 2Gig equipment (and compatible accessories) and will have:
At least 2 control panels.
Glass break sensors ("window bugs") on each glass pane of vulnerable windows and doors.
Door/window sensors on every exterior window or door (including overhead doors).
Contact switches connected to wireless transmitters, for safe doors.
Motion sensors for common areas and the gun room.
Cameras for exterior doors and 'high value targets'.
Door sensors for my gun room.
Water sensors in the laundry room and basement.
...and more, including a door sensor on the shed with my lawn equipment.
