I think some of the biggest cost in manufacturing the PS3 was obviously the Bluray Drive and the Cell chip, but also I think it was the XDR RAM they were using.
Nintendo can find a much more efficient chip that is Power based with some cell built in for a cheaper price than what Sony has to charge to recoup Cell R&D, Manufacturing & Usage.
They can also find RAM that is just as good if not better for cheaper, like what they are using in the 3DS, and I'm sure that is likely their plan. Sell 3DS by the truck load and lower the manufacturing cost of their new Favorite RAM.
As as someone already mentioned, Bluray probably will not be the way they go, but I doubt they will use a standard DVD either. They will try to go with something heavily proprietary to stall the piracy for as long as possible and maybe incorporate some of their Holo tech if possible.
Nintendo could make a system capable of what the PS3 is capable of and much more for cheaper than what Sony is manufacturing a PS3 for today. If Nintendo was aiming for a $299 price point with tech they finalized earlier this year, I would expect atleast twice the performance of the PS360. I wouldn't expect it to graphically blow the PS360 out of the water or anything, but the game would be to leap frog current HD consoles just enough for long enough to be the lead console in multi-console dev and then force Sony & MS to leap so far over Nintendo's effort that that they will hopefully be too expensive to develop for and instead they get up ports from Wii2 instead for the first few years of their existence.