I too did a lot of research before I purchased my security system and monitoring service. It is very common in my area to receive huge discounts if someone who already has a company's system refers you. So, if you know someone who already has a system, ask them to do so.
That being said, there are a lot of variables as to what you will pay. In our case, the house was pre-wired for a system which meant all of the window and door contacts were in place and there were already connections to have motion detectors. Since I had pets, I did not want to contend with constant activations, so I asked whether I could exchange the motion detectors for additional door contacts to protect my garage and 2 remote key activators. Our company had a basic package which consisted of a certain number of door, window and motion detectors, carbon monoxide detectors, panic and medical activation and hard wired smoke detectors with back up battery and one control panel and a year contract for monitoring.
They gave me the system and exchanges free, with free installation if I extended the monitoring for 2 years, so there is room for negotiation there as well. Further, I discovered you can get a system upgrade there after when you research other monitoring services after your contract ends. Often other companies will tell you that you have old technology and they cannot monitor it without upgrading which they charge you for any ways, so you get cheaper monitoring on a per month basis, but you pay for it with the upgrade. So return to your original company to extend your contract, they upgrade for free and continue to charge you the same monitoring fee. And make sure they offer a lifetime warranty on all of the equipment.
Make sure the monitoring is local, not regional, so fire, police and medical assistance is contacted immediately without delay. And, run the test annually on the back up battery. If it is low, contact the company, mine sent me one for free (yeah okay, I paid 50 bucks for the first one because I didn't know they would send me one). Also, another security system scam is to offer regional monitoring at a lower rate with a sneaky activation fee that makes it about the same rate as the major providers locally.