Any authorized dealer is supposed to sell them at a minimum price, so you should be paying the same price if you want to buy from an authorized dealer, not including coupons, free shipping, etc..  Katadyn is a Swiss company and the US dollar keeps on going down compared to the Swiss franc, so Katadyn prices keep going up.  I'd recommend getting whatever you want now from a dealer you trust, because the prices are about to go up again.  

When we started stocking the Pocket, it was at $280, then it went up to $320, and it is about to go up to $380.  The other products aren't quite as bad, but a lot of them are set to go up at least a bit.