Private security is not a constitutional problem. If you want to sniff the spectrum near your business, that’s just fine. The only problem comes when private networked surveillance grows to a scale (like Flock) where it’s an unregulated dragnet ripe for abuse, selling access to the government or nefarious private actors.

I am very much for small scale, non-networked, private surveillance. NVRs are a great way to have peace of mind without sacrificing your privacy. Your private IMSI catcher idea is also fine. (Just be aware that many cops probably won’t do anything unless it’s like six figures or more in losses, they often won’t even track down stolen cars with trackers on them.)