If you have a fair understanding of electronics installing an alarm isn't that bad. Takes a fair amount of time finding the wires you will need to tap but thats about it.

Circuit City as well as most other places do charge for alarm install. You just don't know it. Having worked at CC in the past I can tell you that when you see the prices on the wall with free install next to them the install price is already figured in. At Circuit city they used to ring up alarms like so. Listed price on the wall $349.99, they sell you the alarm for $249.99 and tack on $100 in labor for install. You still end up paying the 349.99 and thinking you got a "free install" kinda tricky but no one really notices it.