Wired's GameILife has an
interesting piece up about the eventual pricing of the
3DS in America. We know it'll be 25000 Yen in Japan, which is roughly $300, but it's not necessarily that cut and dried. It's far more likely the 3DS will run $250 in the States due to dollar-to-Yen fluctuations and the competitive pricing of portables in this market.
The 3DS might still seem a bit steep at that price but it's important to remember everything the portable does--gaming, social networking, augmented reality, 3D pictures, Virtual Console, etc. While lower-spec iPhones and similar smart phones run in the same price range and offer some of the same functionality, the fiddly little apps you can play on them can't begin to compare to the games on the 3DS or even the PSP. Unlike the previous DS models, the 3DS contains relatively modern tech--for the first time in a while, Nintendo is putting more expensive components and features in their new handheld, so if it launches at $250 I think that would be pretty fair.