Exactly because Sony can't have the idea that the price actually rose, is why the price of the 80 gb is going to be 500 dollars when it's sold alone after the limited edition.
Here is a more convincing explanation if you still didn't get it:
The PS2 was dropped in price to get rid of the old big ones in time to sell the new ones and then the new ones took the place of the old as the standard.
They are getting rid of older models. The problem is the 60 gb ones hadn't sold out so they had to do it like this.
Thanks to Blacksaber for the sig!