Well, I don't think it would cost much more than $50 to create a chip with the processing power of a gamecube x 2. The wii probably cost nintendo $100 to make and a further $20 to ship it around the world including controllers and wii sports.
The rumor that I am happy about is that SHARP is providing the LCD 3D screen, as it is a known fact that Sharp makes the best display technologies.
I see this new DS costing $220 - $250, having a full suite of downloadable apps on launch ( if it is compatible with DSi as seemingly indicated, then it must be compatible with DSi Ware). I also expect it to have a much larger onboard memory, somewhere in the region of 8GB (the absolute minimum for phones now. which costs roughly about $2 per 8GB at this moment).
This system is going to be beautiful. It will be the first nintendo Handheld I owned since the GBA.