Over 9000!!!
Just kidding, but I think it should be around but above 200 dollars because, like you said, sony isn't releasing a PSP2 so far, but they might reveal it TGS. But if they do, I'm guessing the PSP2 would cost more than the 3DS would at launch so above but around 200 still sounds good. Also, if Nintendo release the 3DS around 200$, people can justify a purchase of a DSi or DSi XL. I'm thinking Nintendo wants to sell the DS handhelds like how Sony sold their PS3 which was selling several models and letting the best one be a little bit more expensive than the cheaper or cheapest one.
I can't see the 3DS being over 300$, although I think that is a justfied price for such an advanced system. I'm pretty sure Nintendo played around with the 3DS hardware to find the most cheapest and durable component. However, people are really impressed by the 3D, but to what aspect I'm not sure. If they are just impressed that its 3D and it works than the 3DS should be under 300$. I don't think graphics cost a lot for the 3DS because the smaller screen and resolution of it is could make the graphics look better than it actually is if it was to be bigger.