I saw these on ebay and made one myself out of a plant pot and some pure wool carpet in the bottom/sides and on the underside of a rubber auto polishing disc.
I had to make it myself as I live in the UK and postage would have been very high for the official plant pot ;-)
I have used my version of the polisher for about 2 years now with ball polishing paste by Arimith and it works fantastic.
Just spin 3 balls at a time for about 20 seconds with a few drops of polishing paste and then tip them out and wipe off haze. I use a 12v cordless drill and that seems to be fast enough.
I just wish I could get hold of one of these for $30 in the UK they are a great idea.