Alarm Systems

Stop and ask yourself why:

Why am I considering getting an alarm system?
Is it because everyone I know has one?
Am I concerned over damage to my property?
Am I concerned over theft or damage to my property?
Am I concerned for the safety of my family?
For insurance purposes?

The degree of protection can vary considerably for anyone of the above reasons. The prime consideration is the most valuable assets you will ever have, your family, once their protection is considered then you can move forward with whatever your economic situation may dictate.

Security Alarm Systems have many uses, your reason may only be one of them, you should consider their full value when making your decision. 
Was your intent to use the system while you are away, or also while you are home?
Do you want the protection around you and your family whether awake or sleeping?
Would you like to place the system in an annunciation mode, to alert you if any doors are opened, alerting you to someone entering, or possibly a small child has left?
Would you want the system to send a silent alarm to the police should someone force you into your home?
Would you want the ability to send a panic or medical request for police assistance?
You can now see the potential a system can offer may be far beyond that which maybe had been originally considered.

.Though smoke detection is required by law in most states, its primary function is to alert residents and allow them time to leave the building, thus it is for life safety and stops there. The next consideration is the home itself, what if their is no one at home, how far does the fire progress before noticed? Would you be satisfied someone may see the blaze and notify the fire department for you? The only other answer would be you had a Fire Detection System which would satisfy the law, alerting you if in the house and in either case had sent a signal to a central monitoring facility and help was on its way.

Propane or natural gas detection is another life safety consideration. Leakage could incapacitate the occupants of a household making them unable to respond before or during a fire, the proper sensors would transmit a signal to a central monitoring station for relay to fire headquarters to bring a response. Carbon monoxide gas is considered by most to be the product of a malfunctioning furnace, in reality it is also the product of smoldering material that is not fully combusting. The Carbon Monoxide Detector is just another life safety device that when monitored would have brought a response.

Environmental Monitoring is another aspect to consider.
While you were away from your house, did your plumbing start to leak?
Do you have a sump pump that malfunctioned or did not function?
If it is winter, has your furnace shut down causing the temperature in the house to drop possibly below freezing?
If it is summer, has your air conditioning failed causing the temperature to rise to unbearable levels?
A water detection  or temperature sensor would have detected the above and notified the central station who in turn notifies someone you designate to resolve the condition.