Idea for Cheap Alarm System

[EdwardATeller <sorry_no_email@xxxxxxxxx>]

I'd like to have a simple alarm.  It could be as basic as a motion
detector that sets off a loud siren.  I think that would scare off the
majority of intruders.  We come in through the garage, so I would
just  throw the circuit breaker to turn it off.  If anyone knows a
product like this, I'd love to hear about it.

Then I started thinking about something a little more elaborate.  What
if you had a cell phone attached to the motion detector that could be
set to dial a number if it were set off?  For example, it could dial
911 and play a recorded message saying the house address and there was
a burglary in process.  Or it could dial my cell phone, and then I
could decide if I wanted to dial 911.  A Virgin Mobile cell phone
works out under $6 a month, much cheaper than a monitoring contract.