I've recently had a series of quotes from local and national firms for an alarm system and have just decided to go the DIY route. Partly because of the costs (both installation and ongoing maintenance) and partly because of the lack of insurance discount for a professionally installed system.

The DIY system I've selected is less than half the cost of the cheapest professional system and is the exact same system which one of them proposed to install. It can be easily installed with basic DIY skills and will call up to 4 phone numbers as well as sounding an alert at the property when triggered. These numbers can be your mobiles or friends and family with keys. It's easily expandable and wireless except for power and phone lines.

I won't post details of the exact system here in case in breaks forum rules. PM me if you want to know more details.