ParaZapper
Unfortunately, I have not been able to check out those e-bay zappers. The truth is that any zapper is beneficial but what everyone needs to consider is to buy the best zapper that fitsyour budget and needs.
The tendollar zapper from tendollarzappers.com is a good little unit for basic introduction but it has definite limitations. WHile single frequency zappers do work, single frequency is a concern. Two or three frequencies is better.
The ability, not only to add but to support accessories such as footpads and paddles at the same time is a major benefit. Those who use augmentation footpads will definitely experience better results provided their zapper is strong enough to support the additional output. Adding footpads to the tendollar zapper or many other cheaper zappers is like putting a Chevy 4 cylinder engine in a Jaguar. The power is just not there.
The best zappers will use banana plugs to connect the electrode wires. Cheaper made zappers have hardwired connections and alligator clips. I would avoid these whenever possible.
Many cheaper zappers use cheaper parts and take shortcuts on the inside. I have been sent many zappers that have the circuit boards flopping around on the inside with wires hanging on for dear life. Also many zappers use cheaper 10 percent or 5 percent tolerance components that degrade the quality of the unit.
My advice is that you should consider carefully before buying.