My Brother has installed a system he got at Radio shack in his home. The system is not monitored, but I think it could be if he wanted to set it up.
Another thing to keep in mind if you do go with a monitored system is to try and avoid signing a monitoring contract. The company that I use simply charges me a month to month rate and I can drop it at any time. Some companies offer slightly lower rates, but try to lock you in for several years of monitoring.
http://www.radioshack.com/category/i...goryId=2032330