I don’t think you can buy one as a citizen. To me this is purely illegal government sh!t.
From the article -
“At the RSA Conference last week, Pwnie Express demonstrated their IMSI-catcher detector.
Building your own IMSI-catcher isn’t hard or expensive. At Def Con in 2010, researcher Chris Paget demonstrated his homemade IMSI-catcher. The whole thing cost $1,500, which is cheap enough for both criminals and nosy hobbyists.
It’s even cheaper and easier now. Anyone with a HackRF software-defined radio card can turn their laptop into an amateur IMSI-catcher. And this is why companies are building detectors into their security monitoring equipment.”