From the UK, what about the paraZapper?

Hi, I am looking for a Zapper (my first buy). Has anyone tried the "para Zapper" adviced here:

http://www.paradevices.com/parazapper_quality.html

They claim to have improved Dr Clark's zapper. Why everyone seems to talk about the terminator one. Is it better?

I live in the UK, does anyone know where is the cheapest place to buy it?

Thank you,

Sarah