Alarm Systems:

I have never had an monitored alarm system that did any good. Buy the time the monitoring company calls you and you get to your place of business the crooks are gone.

I usually install an alarm system with a very loud bell or horn to scare away intruders. I put up signs that say "alarmed and video monitored". The noise keeps the violators out, and/or reduces their time inside.

I would make exceptions for some types of business with high theft occurrences such as pawnshops, jewelry stores etc. The lack of monitoring keeps cost down.