The section on Security in the Sixth World in the 5th ed book specifically states that magic barriers are an extremely cost-effective astral security measure. While no prices are given, in SR4, it specifically mentions that firms often do wards, and a ward takes (Force) hours to complete. One magician can ward an area of Magic x50 cubic meters in one go, and multiple magicians can pool their power to ward larger areas. Those firms typically charge 100 nuyen per hour (per magician) for the wards, which last for a number of weeks equal to the number of hits on the Magic+Willpower test. In other words, wards are dirt cheap, and anyone who has a few hundred nuyen every few weeks can afford at least a force 3-5 ward on an office or something, especially if they're a mundane. So you should expect wards to be fairly common in areas where the individual has the means to get them. Wards aren't like high tech security systems. They're the astral equivalent of the maglock.