I worked as an installer for a few years.
the alarm is only as good as the installation. What type of crimp connectors did they use. Did they strip and solder? Did they use scotchloks?
In any case, the Prestige alarms were not very expensive at the shop's price (under $20 for the whole unit, IIRC), but they charged a pretty penny to sell you one. They were as reliable as any other brand, though the remotes weren't the most attractive compared to others.
If I were going to get another car alarm, I'd buy a Directed Electronics Viper brand alarm. They were the best.
As for the cheap prestige ones, I actually used one to make a remotely operated paintball mine. I had a pressurized canister of paint hooked up to a lawn sprinkler solenoid valve and spray head. This was connected to a relay on the siren output of the alarm.
The whole thing was powered by 2 lantern batteries inside a tupperware container spray painted camo.
I had a piece of rebar driven into the ground and strapped the alarm's shock sensor to it.
When armed, anyone running within a few feet of it would set it off. You could also manually trigger it with the panic button on the remote, or disarm it to allow friendly players to pass.