Radio shack used to have an alarm that paged you for 30 bucks! It was not the state of the art systems we see today but it work great for my old car. You had to install small transducers in each
door jam, the sound of someone pushing in the old style
door button would set it off. Did not work well during thunderstoms, but what can you expect for 30 dollars! The pager went off instantly but the siren (sold seperatly for around 15 bucks) was delayed about 20 seconds. The only way to disable the alarm was to turn on the ignition. This saved my stereo a few times. I bought it after someone stole my Holly carburator. One time the pager went off at 3:00am and I yelled at the kids from my third story apartment building window. They could see I was not going to be able to get out there instantly so they were taking their time to leave, but after 20 seconds when that siren went off, they hit the ground running. It was worth the $30 just to see them run so fast! I am not sure why this product was discontinued, it was almost too good.