Was watching academy live tonight

on the golf channel. Peter Kostis was on talking about many things, eventually he came to talking about the correct path for the putter etc. and he brought out his new training aid, called the "Putting Professor", anyway, heres the website...puttingprofessor.com It looked like a great tool and could really help with a shaky path. I know Vijay has started to use it..(which might be a cursing and a blessing at the same time) But I wanted to kind of see what you think is a good putting training aid. I know the "Cameron Cube" is going for about 175 now on ebay.. which is a littttttle out of the price range. Any comments would be greatly appreciated.