Blasting a plug to clean it is an old concept that worked rather well during the time is was most used, the 60's through 80's. Your comments about the cost of the equipment needed to clean a plug are most sage. In the vast majority of cases it's not worth the effort. Those that have a large number of engines or a shop where such a quantity is in place is where one would usually find such tools. Typically those having one of the old plug cleaners would be "old school" in outlook or involved in racing.

For most, dipping in carb cleaner, use of a a brass brush, followed up with a brake cleaner rinse and a blast of compressed air would suffice. After that proper tuning would clean the rest during extended run times. With all the plugs I've handled, I have yet to see one become "worn out" in less than 100 hours or so. Even those would be usable for longer once the electrode was dressed and adjusted. Typically they are broken before they are worn. Generally that was done by banging the electrode on a hard surface to adjust the electrode. The ceramic develops micro cracks when adjusted that way, causing the plug to short out to the hex base.