basement finishing

Hello all,
Someone in our neighbourhood died of CO poisoning recently. Looks like CO poisoning is killing a lot nowadays. So I'm thinking about installing a good home alarm system with the CO sensor.

So all I need is a system that is easy to operate and customizable. I'm thinking of 8-10 cameras, some other sensors, door lock and alarm, etc.

Yesterday I found a home alarm systems company in Toronto from the web and it seems pretty good. So I would like to know how much it'll cost for an alarm system like this?
I know the rate will change according to location and company. just wanted to know the average rate.

Thanks in advance!