I have seen many, many dive shop analyzers that are way out of calibration or have bad sensors or just never work right. Some shops do have analyzers that work great, but you cant count on that. In addition, you never know where you might be getting a fill or renting a filled tank.. I personally like to have a known, trusted source for my gas analysis. If the analyzer is reading "37" I want to know in my hear of hearts that its 37, and not somewhere around that.. Owning your own analyzer will bring you peace of mind, and true quality gas analysis if you do it right. If you stop and think about it, even someone diving air only can benefit from an analyzer. Owning your own analyzer can also save you time and headache. Example - Early in my Nitrox career I somehow had a label peel off a tank in transit, and I could not say with absolute certainty what was in the tank. Luckily I had time to schlep to a near by dive shop, and analyze the tank and make it back to the boat in time to make the dive. In many cases I would have had to call the dive. I bought my analyzer the day after this incident. There is no replacement for owning and knowing how to use your own analyzer. the consequences just are not worth the few hundred dollars a good analyzer will cost. Also, on this same note, I would strongly consider a CO analyzer as well. It does not pay to cheap out on the fundamental tools of diving and I believe always being certain of what you are breathing is worth spending your money on.