You have all sorts of insurance on your business, your assets, and likely on your own person. Think of commercial building security as another form of insurance.
Your security measures may not need to be that complex. Start with a proper security needs assessment. This will give you a solid foundation upon which you can build a custom system.
Your point-of-contact at your security company will advise you on the various configurations possible. Consider their recommendations and select the right system for your needs and budget.