Well maybe it's still the same faulty batch and the price only goes up because these are the last ones. From what i read GPH stoped the wiz production long time ago now.
That sucks. I bought my Wiz from ThinkGeek not even a month ago for $99. At least at this point, you can get a crapload of Geek points if you do end up buying it from there(2k points compared to the 750 at $99). Otherwise, be sure to stalk eBay.