You can't go wrong with a PDA-1. Mine has been a great introduction to the hobby of distilling. I also recommend Amphora's book, The Compleat Distiller, as well as their other books (I own them all).
Recently I built a still, Harry Jackson's design which you can find at this link: http://distillers.tastylime.net/library/BAPHS/index.htm
It was a fun build and challenging as I'd never worked with copper before.
I'd still go with a PDA-1 first if you want to begin distilling right away, and then if you get the itch, build something yourself.
As for potato vodka, I don't know much about that but I've guzzled a lot of grain based stuff.