cheap zappers?

I'm wondering about the efficacy of the cheap zappers at dr. clark's page. there is one that runs off a 9 volt battery for around $20. is this suficient?

i'm a little skeptical about the zappers in general too, and am wondering what people think and have experienced. I can understand how they might be effective. But what about side effects? The body is an electromagnetic circuit. How does this type of device affect health overall. I mean, chemo-therapy can reduce tumors but it also has very negative effects on the body.
And I am always skeptical of medical devices and contraptions that cost upwards to $400.

thanks for any info Tweet