I like Alarm Relay
I like Alarm Relay. They have great low annual prices, and their monitoring is great. I get a call each time my alarm goes off(usually it happens by mistake). they can use any hardware you may already have like I did with my mom's ADT equipment, or they can sell you a set up like what i did . Its the usual price, mine ran about $550, but when I compare to my sister's $60/month from adt, buying it out will pay for itself in just one year. But make no mistake, if you need onsite help, thats where the cost comes up. This is great for existing system or if you are a good DIY.