That's the one thing I cannot agree with, even if the rest is 100% true. A healthy amount of thrift is a great virtue, and absence thereof is one of the major reasons I dislike the current medical system. It's the same with healthy (not excessive) skepticism. In proper moderation and balance, these two related attributes are not only great assets, they are actually the driving forces of progress. Would multiple frequencies really be better? I'm glad you are researching, and I think you may be right about the lower frequency penetrating better. In that case, a 2500 Hz zapper might indeed be more penetrative than a 30 kHz zapper.
But there are still some questions that come to my mind in this case. For example, is this high of a die-off rate potentially more dangerous? The 30 kHz model is somewhat fatiguing to use, but I've heard (a few cases) of people getting seriously incapacitated from the toxic die-off triggered by super-penetrating models. Perhaps a lower power is actually preferable from a safety standpoint. See warning notice at the bottom of this page: http://www.royalrife.com/zapper727.html
As to quality, I think if it's functional, simple to use, portable, and fairly sturdy, that counts for something quality-wise, regardless of price or special attributes.