In the case of our church cost was not the issue. I donated the alarm system. The point is that many such institutions have plenty of technically knowledgeable people who can do for the church that for which a private company might charge three or four times the cost of the materials. This isn't meant to fault alarm dealers. They need to make a profit from their labors. However, they don't have a *right* to insist that no one but they do alarm work.
Until you've been involved in church work you wouldn't understand. By the way, by "on staff" I did not mean to imply "on salary." In our case these were volunteer staff. We had over 100 people working at any given time but only a few were paid employees. This is quite common among growing, modern churches.
This isn't the main point though. The real issue is whether anyone except a paid alarm installer can or should install an alarm system. For several decades I've proven that laymen can successfully install their own security and fire alarm systems. This includes commercial as well as residential systems. You guys can argue and nitpick all you like but it won't change the fact that DIY is a valid and growing portion of the electronic security business.